I ran a game from 1-20, with two melee types and two wizard types. In any situation that wasn't just mopping the floor with a bunch of chumps, the melee characters were doing just fine while the casters alternated between less effective and ineffective. Anything worth fighting is going to have legendary resistance, which gives it immunity to the best spells and does nothing to impede warriors. Spellcasters can usually get around enemy resistances, but weapon-users can always get around resistances; nothing resists a magic sword. Etc, etc.
Of course, the relevant part of the topic at hand is how NPC spellcasters fare against martial PCs. They struggle. PCs have better stats, and class abilities that boost their saves or otherwise let them ignore effects. A high-level fighting monster can at least deal some damage. A high-level caster NPC or monster often does nothing, because the PCs make their saves and spells don't deal very much damage regardless.
Any rule that makes it harder for spellcasters is simply unnecessary.
No, it isn't unnecessary. Perhaps in your game, you choose to ignore rules to improve the wizardry experience, which, for the first time, I read someone complain of as lacking power (!). Seriously, people that cast
wish can't complain about being underpowered. I've run too several campaigns of D&D 5e, and, while I'm not a greybeard (I'm 33 years old), I've played D&D for a long, long time. I started with AD&D, and as one of the grognards say, there use to be much harder rules against spellcasting, like, say, you lose any spell you're casting if you are punched in the face.
You. Lost. the. friggin. spell. Here you can cast in melee without any type of hindrance. You don't even need to be holding a weapon to defend yourself.
Furthermore, there
is no new rule. If you bother on reading what I've being saying instead of closing in a war trench position, you will know that actually there is actually several rules in the PHB that support my claim. I'm going to quote them to you:
PHB P.203 said:
Components
A spell's components are the physical requirements you must meet in order to cast it. Each spell's description indicates wheter it requires verbal (V), somatic (S), or material (M) components. If you can't provide one or more of a spell's components, you are unable to cast the spell.
Verbal
Most spells require the chanting of mystic words. The words themselves aren't the source of the spell's power; rather, the particular combination of sounds, with specific pitch and resonance, sets, the threads of magic in motion. Thus, a character who is gagged or in an area of silence, such as one created by the silence spell, can't cast a spell with a verbal component.
Bolded is mine. As you can see, the rule actually calls the ability to speak clearly as a prerequisite, because the magic isn't in the words themselves, but on the pitch, resonance
and the combination of sounds. And then immediately quotes possible sources of interruptions to the verbal components. As there is no specific rules for gagging a creature, but it is specifically quoted at a possible source of impeding verbal components, it falls under the following rule:
PHB P.193 said:
Improvising an action
Your character can do things not covered by the actions in this chapter, such as breaking down doors, intimidating enemies, sensing weaknesses in magical defenses, or calling for a parley with a foe. The only limits to the actions you can attempt are your imagination and your character's ability scores. See the descriptions of the ability scores in chapter 7 for inspiration as you improvise.
When you describe an action not detailed elsewhere in the rules, the DM tells you whether that action is possible and what kind of roll you need to make, if any, to determine success or failure."
So, if you want to gag a creature with your bare hands, there is no specific rule, and falls under Improvising an action. Granted, the DM cant deny said action, but it is there quoted as a possible source of interrupt verbal components, so you are immediately suspending one specific example given by the rules, and furthermore, harming suspension of disbelief in an attempt to "balance" the gameplay
ignoring the rules. The best course of action isn't that: it is to allow such tactic (call it choke, call it something else, like grabbing the mouth of the spellcaster), and model the action in such a way that is more difficult than simply grapple the character.
A grapple falls into a
contest rule, and it is a great
starting point to further model the action, as it allows the enemy to resist
and to escape. Even more, it requires the grappler to have at least one free hand, so it isn't an action without consequences. Quote:
PHB P.195 said:
Contests in Combat
Battle often involves pitting your prowess against that of your foe. Such a challenge is represented by a contest. This section includes the most common contests that require an action in combat: grappling and shoving a creature. The DM can use these contests as models for improvising others
Grapple rules:
PHB P.195 said:
Grappling
When you want to grab a creature or wrestle with it, you can use the Attack action o make a special melee attack, a grapple. If you are able to make multiple attacks with the Attack action, this attack replaces one of them.
The target of your grapple must be no more than one size larger than you and must be within your reach. Using at least one free hand, you try to seize the target by making a grapple check instead of an attack roll: a Strength (Athletics) check contested by the target's Strength (Athletics) or Dexterity (Acrobatics) check (the target chooses the ability to use). If you succeed, you subject the target to the grappled condition (see appendix A). The condition specifies the things that end it, and you can release the target whenever you like (no action required).
Escaping a grapple. A grappled creature can use its action to escape. To do so, it must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check contested by your Strength (Athletics) check.
So, as I've said earlier, I'm not claiming that a grapple is the rule to impede spellcasting.
It is a model to improvise the action I want to make, as per the Contests in Combat rule and Improvisation rule. And, in this model, you need at least
two attacks, and one of them at disadvantage; and I've actually quoted the disadvantage/advantage math: in the best case scenario, it doen't have advantage
ever, where other tactis have. Furthermore, if it were a concern over balance, you could claim that the grappler needs
two free hands instead of one, thus further impeding him to take their most optimal actions
too:
weapon attacks. So, as you see, it isn't even a win-win situation: it is an option you can take, a useful one, but not always the best one.
You can, rightfully, disagree with my specific way to model this action: you can model it in some other way, like an attack against a Constitution or Strength saving throw, a Concentration check or anything else, or even an ability check against a DC that goes as high as the DM wants to. You can What you can't do is
ignore the rules because you feel that the wizards are weak (!). Or you can, but
you are going against the rules of the game.
Furthermore, as someone said, there is a ton of spells that don't require verbal components. I took the work of counting them: they are 22 for the wizard only, the allegedly most affected by these rules, and
7 of them are cantrips and 5 of them are level one, like
Ice Knife or
catapult. And, as the same guy quoted, there is the spell
freedom of movement, that lasts for an hour and it doesn't have concentration, and makes the caster immune to grapples, or at least escape them using 5 feet of their movement.
So it isn't that only a few specific builds can survive being silenced: you just need one cantrip and one spell, and that's it, although it is true that only a few specific builds can attempt this tactic (Strength fighters and Barbarians) with some degree of success. It isn't the equivalent to one-shoting a caster or a dragon aiming to the neck with an axe.
As a coda, you said that nothing is immune to a magical sword. You are wrong, a flying creature is immune to them, because the sword can't hit it. Suddenly, that flaming demon is out of reach and flailing the fighter, who can only respond with javelins for half the damage. Or needs the wizard to cast
fly on him. AND, if you are counting magical items, that aren't granted by default, you can always
create a ring of Freedom of Movement, whereas the fighter needs the good will of the DM.
Lastly, I compel you to look better at what you do in a game where a wizard is considered weak. It is true that it isn't the old "god mode" of 3.X era, but it is
far from being a weakling. Someone that can cast Wish or polimorph itself into a T-Rex with a 4th level spell isn't, by any means, weak. And I compel you to revise the importance of gangs in 5e, as it is much,
much more effective to toss several creatures than solos. Yes, fighters and paladins are better dealing with a Solo legendary monster than a wizard,
as it should, but mobs are better handled by your wizard in many,
many ways.
As I've said, many of you are objecting on principle, without any real concern of balance or RAW. If you come with an alternative to choke or gag or impede in some way the use of verbal components as a martial, more balanced, more ellegant, more in tune on the ways of 5e, I'll apologize and recognize that you are really concerned on balance or the rules of 5e. If not, I believe that nothing I can say can convince you, and I'm certain that I've never would play in such a restrictive, homebrewed game that ignores explicitly called rules, favoring spellcasters.