Primary caster is better than just caster, if that is what you are talking about. But while that logic might work for 17th level characters, 1st level Rangers and Paladins have 1st level spells just like the full casters.
On top of that, 1st level Rangers can actually cast more spells per day than any other class* and 1st level Paladins can cast the same number as Bards, Sorcerers, Clerics and Druids. If you assume PCs are using all their spell slots, Rangers in tier 1 are keeping up with full casters pretty well and in some cases will still be casting after those guys have run out of slots.
*Technically a 1st level Warlock who gets 3 short rests can cast the same number as a Ranger.
Really my point is this - if you are comparing spell casting classes to non spell casting classes you should compare classes that cast spells to classes that don't cast spells. A ton of both the Ranger and Paladin capability come from their spells. Calling them "martials" and excluding them when trying to demonstrate how relatively strong or weak "casters" are is a bit disingenuous IMO. In terms of abilities, capability and general play style, a Paladin is a heck of a lot closer to a Valor Bard or Bladelock than they are to a Rogue or Monk.
The heart of this ancient debate comes down to the fact that most "martial"/low-magic/non-magic characters are effective in limited ways. Let's look at a level 5 Fighter (no subclass).
He is effective in that he has more hit points than most other classes, can use any weapon, wear any armor, has a minor self-heal, and can grant himself an additional action in tough battles. Like most (but not all) weapon users, he can make a second attack in combat. If enemies try to push him, knock him prone, or attack his physical body, he's somewhat more resistant, and he has a few skills that can be employed. With the right weapons, he can dual wield more effectively, increase his accuracy, ensure he never fails to deal some damage, or provide limited battlefield control to those he hits.
In contrast, the level 5 Wizard has much lower hit points, few weapons, no armor and must rely solely on magic for attack and defense. However, he enjoys several at-will cantrips, which can be seen as low damage attacks (most with built-in weapon masteries!), or provide useful utility, like torchless light or being able to grasp something from a distance.
A few times per day, he can do things the Fighter cannot, such as strike multiple foes at once
control enemies
debuff enemies
buff allies
protect himself from harm
provide even greater utility
I once postulated the scenario of defending a small town from an oncoming horde of foes. It's possible that the Wizard could do any of the following:
*scout enemy positions with Fly/Invisibility/Polymorph.
*create arms and armor for the townsfolk with Fabricate.
*create fortifications using Wall of Stone.
In contrast, the Fighter has no bespoke abilities outside of "fight good" beyond their skills. The DM could ad hoc say that they have the ability to lead men into battle or train peasants to better fight
or have advanced strategic knowledge that could develop an effective strategy for the battles (and they really should!), but they cannot match the potential versatility and power of what the Wizard might do.
Now it's just as possible the Wizard can't do any of the above things, and is no more useful than a portable siege engine, but that's still a really good thing to have in this scenario, whereas, the Fighter, despite being a militant class, is actually not very good at killing large numbers of foes quickly.
There are, of course, many scenarios where the Fighter can outperform the Wizard.
But there can be many more where the Wizard can do things the Fighter cannot possibly attempt.
This is where the disparity lies. Again, a given game might never see it, but it's not impossible either. Especially if the Wizard can begin to exert power over the world as a whole.
There can even reach a point where a hapless DM might no longer have any ability to reign in a Wizard without invoking pure fiat if they are not careful, as Gygax warned people about in the 1e DMG. Both classes can fight monsters and have their own unique role in adventuring, but the Wizard has tools which are orthogonal to the Fighter's.
Funny thing:
A fireball alone is not fantastic. But having 5 casters starting with fireball has a significant chance of ending a fight before it really begins.
Lets assume 3 go through. 2 are saved against. That is 32d6 damage (average 112) right away.
Enough to really soften up the opposition quite heavily.
I still think you are correct. The game is better if casters and non casters synergize. And in that case, starting out with fireball is not the best option often enough. But if you are an evoker or sorcerer, you can finish an encounter with fireball very well.
In all these discussions, one thing I find notable is that I see a lot of martials in play, but I see very few non-casters.
Even the Fighters and Rogues are usually sporting some spells from something, maybe 1 in 10 PCs is actually a non-caster.
If the spell sticks. But this is basically what I said. An option. But a mixed party is more successful.
I think the line for me lays in the middle of the half-caster, artificer I consider more caster than martial, ranger more martial than caster, and paladin is smack dab in the middle.
I go with the following if I even need to define them.
I don't bother taking into account subclasses. A fighter and rogue are martial classes, it doesn't matter that they have subclasses that make them a hybrid.
- Caster. Base class has spellcasting
- Martial. Base class gains an ability that improves their weapon capabilities (extra attack or sneak attack)
- Hybrid. Made up of both Caster and Martial, tend to lean on one more than the other.
- Paladin, Ranger. More martial.
- Artificer. More caster.
In simple terms. Martials are riflemen, casters are artillery. Wanna take out single target? Riflemen can do that job for you. Wanna take out bunch of them or suppress them? Call in for artillery strike. You don't really call in artillery on single target unless you are in winter war against guy name Simo.![]()
The White Death's CR was too high for the Russian Army to deal with. They had to bring in a Wizard to defeat him!In simple terms. Martials are riflemen, casters are artillery. Wanna take out single target? Riflemen can do that job for you. Wanna take out bunch of them or suppress them? Call in for artillery strike. You don't really call in artillery on single target unless you are in winter war against guy name Simo.![]()
That's a bit dismissive. I'm not going to be able to convince you or anyone, but let's just say that my experience of the phenomenon was first hand. Once I had experienced it, though, I could begin to think back on a number of separate occasions where other people shared my sentiments as well. People I knew irl.The caster supremacy arguments seem very whiteroomy to me.
After a claim that casters get to rest after every encounter it's hard to take that anecdotal take seriously.That's a bit dismissive. I'm not going to be able to convince you or anyone, but let's just say that my experience of the phenomenon was first hand. Once I had experienced it, though, I could begin to think back on a number of separate occasions where other people shared my sentiments as well. People I knew irl.
Anecdotal is anecdotal, of course. But going through my campaign notes for the past few years (both as DM and player since early 2018), our parties have long-rested about 40% of the time after one encounter; bumping up to 2 encounters pushes that to just over 70%.After a claim that casters get to rest after every encounter it's hard to take that anecdotal take seriously.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.