It depends where you consider Paladins martials. A Paladin's peak is very high if optimized for it. In 6 years of playing 5E the most damage I have seen done in one turn was done by a Paladin-Assassin.
Now casters do get non-damaging options that completely disable an enemy and you can't put a DPR on that, but martials, especially Monks, get some of those too.
This is a myth. RAW, casters were not the equal of fighters and rangers in 1E at any level. This is purposeful. Gygax intended the fighter to be the leader of the party, the knight in shining armor and the hero of the story. The other PCs were essentially meant to be support, you might even say sidekicks. The game designers have even said such on record.
To start with the only time casters could generally use a spell was on the first round before melee was joined. In 1E melee any wizard wanting to cast would have to declare before the round started and would automatically get attacked by any intelligent combatants in range and had to not get hit at all by any of them to successfully complete the spell (DMG page 65).
In terms of DPR, 1E Magic-Users would generally be killed the very first round by an equivalent-level fighter. The only time they could expect to survive a round against a combat-optimized fighter (or ranger) was like levels 5-6 when the fighter did not yet have 2 attacks and MUs had 12-15hp which would usually survive one hit or over level 11 where they could survive 2 hits. In that case they might last two rounds, but they would still generally be on deaths door after 1. That assumes the fighter did not have an 18 strength or double specialization in bows either, if he did even these magic-users would usually be dead in one round.
If the Mage won initiative and used their top level spell, and if the fighter failed his save then they might win a 1-on-1, but that was using a top-tier spell they got very few of where the fighter was reliably killing an equal-level wizard-equivalent bag of hps every single turn, all day long.
Against enemies with less than 1 hit dice fighters got a number of attacks equal to their level, so while a 5th level magic-user could crow about doing 15 damage with a fireball and killing a large group of goblins once a day, the 5th -level fighter could walk into every room full of goblins and attack 5 of them a round all day long.
Fighters also started with poor saving throws compared to others, but at high levels they had the best saves because they improved quicker than other classes, so when the casters were really starting to get game-changing spells they could not be relied on to land against equal level enemies (most enemies used fighter saves).
2E improved this a little bit by getting rid of double specialization for martials and adding schools of magic for magic-users but they were still behind martials at all levels.
In 3E Gish multiclass/prestige class characters ruled combat in general, although combat was so varied and monster resistances so varied that really depended on what you were fighting. For example a halfling swashbuckler, rogue, wizard, shadowdancer could do good damage and be invincible in combat .... unless facing a regenerating undead or barbarian and then he was useless because he could not do enough damage against them to matter.
I play mostly Rogues.
