Is it really my trick? I was agreeing with Dave that rogues will have a hard time getting advantage on a dragon with no one in melee. All you did was point out that it was possible. I don't disagree. I understand where Dave is coming from and why his rogue had a hard time doing damage. You have to set him up to do damage using more party resources, whereas a ranged striker using Sharpshooter like a ranger or fighter doesn't need much set up.
We can toss out the entire strategy you presuppose by having some badass archers/ranged attackers ready to rock and roll on the dragon. That's been the gist of my participation in the discussion. This new concentration mechanic makes melee martials a liability compared to ranged attackers because you have to use that concentration slot to get them in the fight, whereas ranged attackers hammer and hammer hard without much needed assistance besides illumination which everyone in the group needs. I don't think I like melee martials being such a liability. Not real fun for them, not real fun for casters.
A mechanic that punishes players for class and weapon choices is not a good mechanic in my opinion. When it not only punishes the player playing the class and weapon choice, but the caster who has to limit himself to help that player get into battle, that is a mechanic that could use a look from the designers. I wrote my own modified concentration rule that will hopefully take some of the punitive effect away. We'll see how it works.
This is what I'm going to use:
Extra Concentration: Beginning at 5th level, you can concentrate on a second spell that can be no more than half of the maximum level spell you can cast (rounded down). One of the two spells you are concentrating on must be a spell cast on at least one other allied target other than yourself (but can include yourself if the spell includes multiple targets). If you are required to make a concentration check, you make a separate roll for each spell. For example, a 6th level wizard can cast up to 3rd level spells, allowing him to cast and concentrate on a second spell of 1st level or lower. So a 6th level wizard could cast fly on the fighter and tasha’s hideous laughter on an enemy, while maintaining concentration on both.
Ranged is only stronger by default if the DM fails to exploit its weaknesses. Cover plays a large role in this regard (albeit, Sharpshooter reduces this issue by ignoring half and three quarters cover). Also, it's not a given if you're running a more dungeon oriented campaign, where encounter distances will frequently favor melee. Outside, however, unless your campaign world is a giant salt flat, there should be plenty of cover/concealment to exploit, assuming that your encounters start at ranges where ranged combat has the advantage. Most D&D worlds are fairly primitive, so outside of civilization things should be ancient and overgrown, offering plenty of cover opportunities.
Ranged combatants should weave in and out of cover. Rather than performing a suicide charge, melee should approach under cover. If your monsters are using tactics comparable to the red coats in the Revolutionary War, you're playing them sub-optimally. If they are not, then ranged attackers should have a hard time hitting them as they approach.
While Crossbow Experts can melee, melee-specialists will typically out perform them. Shield users will be harder to hit, while two-handed weapon users will be doing more damage per hit.
Admittedly, ranged attackers have an easier time with flying opponents than melee attackers, but there are ways to mitigate this even without caster intervention. Magic items such a a Broom of Flying or Carpet of Flying can make Fly largely unnecessary (certain carpets are even faster than Fly). And flying attackers should be using cover just like other enemies. While getting your one readied attack as a ranged attacker is better than no attacks as melee without flight, it isn't much.
Then there are the advantages unique to melee. Some of the best damage enhancing items are Strength or melee-only items. Belt of Giant Strength. Flame Tongue Sword.
I mean sure, magic items are optional, but then so are feats. And without Sharpshooter and Crossbow Expert, a ranged-specialist is a lot less amazing. Negating the penalties for anything short of full cover and for firing while in melee is pretty huge for ranged builds.
Maybe I'm wrong, but I don't think melee is weaker than range in the larger scope of things. In a white room (or salt flats) sure. But if you're putting melee at a disadvantage by starting typical encounters hundreds of feet apart, then you ought to be putting the range at a disadvantage by placing plenty of opportunities for cover in between. A road may be flat and open, but what about the hills or woods to either side of that road? Melee has its own strengths as well as weaknesses, just as ranged does. Which of those strengths are played to, and which weaknesses played against, will depend very much upon the campaign and even moreso upon the DM.
