No I mean what I said. When talking about classes and damage I think it is difficult to come up with a generalization that applies "more often than not" in a one-shot and I think it is impossible in a campaign that covers multiple levels.
If you laid down specific assumptions you could perhaps do this effectively, but then it would only apply in those narrow bounds which by their very existence rule out the typical game.
I don't think it's hard one bit.
Truestrike is pretty darn strong with a pistol as an opener in combat. After that it is assumed you close.
Sorry but a single shot before you need to reload for a turn isn't a strong ranged option. There's no reason to assume you could close or even that it would be a good idea to.
Don't get me wrong, I think it's a fine idea and helps with your weak ranged options, but it's not a complete solve.
Also A Palding with a Javelin and Divine Smite is pretty strong but an even better option most of the time is Wrathful Smite with a Javelin, although in the Whiteroom it is less DPR.
It's also not very ranged (30 ft), not very sustainable (limited use resource), etc.
At 5th level, not counting Hunter's Mark, not counting Divine smite, not counting Vex, not counting Rage, no counting any subclass ablities .....
Adding all that in doesn't take away the damage you've given up from no offensive fighting style, only a d8 weapon, no damage dealing feat. Assuming level 5 and GWF and GWM that's 2.5+1+3 x2 = 13 Damage per turn before accuracy adjustment.
No it isn't. Even going with a simple Rapier, factoring in a 60% chance and Vex it is higher than that. How much higher depends on the number of foes, the length of combat and the amount of time attacking one foe. The upper limit with a 60% base chance to hit with no advantage and Vex will approach 15 DPR including crits in combat against a single foe for an unlimited number of rounds. Fighting Goblins, yes it will be capped at less, but that 25 hp fireball the Wizard throws on 7hp Goblins will be capped as well.
I'm going to challenge your 15 DPR. A level 5 character with +4 str/dex, a rapier and vex isn't doing 15 DPR. The absolute most I'm getting is 14.3.
Vex d8+4 attacks at base 60% hit rate 5% crit rate. (This is DPR over the given number of attacks, not DPR after them).
2 attacks = 12.0 DPR
4 attacks = 13.0 DPR
6 attacks = 13.4 DPR
infinite attacks = 14.3 DPR
Ultimately you'll typically see closer to 13 IMO.
If you go strict RAW cheese to maximize damage you would go Vex-Nick-Vex with a Shortsword-Scimitar-shortsword while holding a shield. As an alternative a fighter can go Sap-nick-Vex with Longsword-Scimitar-Shortsword and give the bad guy disadvantage on his first attack to boot, way outshining a caster in terms of defense..
I don't agree that's RAW.
These examples are all RAW at 5th level and do not include things like Rage, hunter's Mark, Divine Smite, subclass abilities etc.
But all PC's built with more offensive options get those things as well. There's still a large damage gap there. You've given up a ton of damage to take defensive duelist and use a rapier.
The more relevant question though is whether those abilities being accounted for is enough offense to outperform tanky caster options. Consider a Druid can do 3d10 with moon beam to many enemies every turn. He can also use circle of stars ability to make a d8+4 attack.
That's 13.2 DPR to multiple enemies and an additional 5.3 to a single enemy every turn, while also being able to sit the moonbeam on top of 1 enemy and have them take damage at the start of their turn if they don't move (presumably facing OA's if they do). That's at least 18.5 total single target DPR. If the enemy can't move it can be an additional 13.2 single target. If it can there's the possibility of having to choose between another moonbeam hit and an OA.
The Druid is ranged, has 19 AC to 24 AC with shield spell. I don't think the martial you are describing is doing enough damage to compensate, nor does he have significantly more defense to win on that front. He's less ranged. Etc.
Clerics with Spirit Guardians are similar as well. Thus why I think most martials that don't focus on offense don't compete well against casters.
But if we are speaking in generalities he is going to generally outdamage most full casters in play, whether or not his numbers in the whiteroom are better.
If casters do typical stuff like focus on control instead of damage, then yes. If they focus on damage then I think a cleric and Druid out damage that PC while being just as tanky.
Wizard will be able to with level 4 slots on summon fey. Though they probably are a bit less tanky and quite a bit less reliable given the limited number of those slots, at least for a while.
I think Sorcerer will mostly depend on how one counts AOE damage.
I don't think a bard stands much of a chance in the damage department.