Oh, I am aware of the paladin factor. But one class design or the optimal multiple class design of 2 does not really seem like a point of a comparison to me. Sure we can claim Paladins have unlimited power or No one can nova like a sorcerer can nova but that does mean anything when your trying to build a good druid. My point is its apples and orange because its very rare that the only goal of party member is to just do the most damage. They usually want to be the best of a concept, best warlock scout, barbarian tank, best anti-magic tank sorcerer, best healer. So saying my Fighter/Sorcerer is not optimized against paladins is not really relatable, because I made a good build but I took mithril plate armor so I don't have disadvantage on stealth rolls and spellguard shield to defend against magic where I could have take +2 plate and +3 shield for 5 higher AC or +3 weapon for greater hit with booming blade. I mean we had a berserker Barbarian playing for part of the dungeon with a +3 great sword and bracers of defense who was out damaging me too if that's your only qualifier but took every spell hit and swallowed it in his massive HP. I did not want to play a barbarian.
more than anything I was trying to point out that Dexterity is more than its entries because dragons and other casters as well as any homebrew monsters or traps tend to lean that way with fire and lighting being more common than poison and cold. Their maybe more cold traps but most GM will tend toward lighting in metal rooms and fiery explosions. Sure poision needles and gas happen but cold traps are rarely used in my experience.
I hardly see what you are saying. About the fighter, as I've said, Dex in higher levels could be a factor, but it is a small one. And as I've said, if your campaign has multiple blaster casters, yes maybe Dex is a better save than, by the sheer numbers, is.
Also, traps are mean to be discovered more than to tax the characters. Perception + Investigation+ thieves' tools are the way to go. Also, as I've said, most traps involve attacks from them, not saving throws. The rest is between poison and others. For example, take the spiky pit trap. Or the darts from the walls. Or the rolling boulder. There isn't a lot of "fireball" traps in the DMG nor Xanathar's.
And again, if a DM likes to throw lots of blaster casters, yes, your campaign will indeed involve lots of dex saves. The same way that a campaign with psionics and mind flayers will involve lots of Int saves.
And I didn't even account for magic items, nor feats, nor even archetypes. And the sword and board fighter of my example wasn't precisely a pure damage build (I would choose a battlemaster Polearms or Crossbow master instead). Even with shield master I would do more damage via critical hits. So if I had access to all of that, numbers multiply. A +2 sword in a level 20 fighter means 32 extra damage in the first two rounds of a combat, and +8 per round afterwards.
I, as a player, play with a Variant Human fighter, a Lance and board battlemaster with lots of Athletics (+10 at level 6) without any magic involved, so my bashes are mostly successful, even against larger creatures. I have also a lot of tools and skills, because of human, Prodigy, Folk hero and Battlemaster. And also at level 6 I'm the mage killer (no feat required, only damage and smart play). As shield master, I usually knock enemies prone, further increasing my chance of hit, and decrease theirs.
Spell casters usually can't keep up with me. A hobgoblin devastator isn't effective against me. Even a beefed up one, I often One-shot them. My shield master feat is useful, but mostly because of the bonus action. I don't lie to you, if I've made 3 Dex saves is a lot. And I'm not even a damage focused character, but a skill-tool based one.
