I'm starting to feel like the "Fighters fight" is part of why they don't seem to know what to do with Rangers, beyond making them a sort of default "Fighter/Rogue/Druid." Which is (weirdly) what a Bard was in 1e, but I digress.
We're trying to keep fighters as the supreme combat class, and so the ranger can't step on the fighter's toes, and so we can't beef up the ranger with combat feats. We can't give the fighter too many non-combat abilities because then it will end up treading on the toes of the ranger (or the rogue).
I go back to my initial premise that most of the fighters in fiction and myth are WAY more than just their combat prowess. Take Lan, from The Wheel of Time. Ignoring (for the moment) the supernatural powers he has from being a Warder, and just look at his combat and non-combat skills. He's a master swordsman, a superb archer, a tracker, survivalist, horseman, with skills at sneaking, scouting, intimidation, persuasion, deception, and also an accomplished courtier. Is he multi-classed? The same assessment can be made of Fafhrd, Faramir, Boromir, Aragorn, Simon Snowlock (Memory, Sorrow, and Thorn), Prince Arutha or Tomas (The Riftwar), Beowulf, Arthur, Lancelot, and even characters like Kelemvor (even ignoring his Werepanther curse) from D&D's own Avatar Trilogy.
I had to refresh my memory and I now admit that Conan does indeed both have the ability to go into a "Fighting madness" (Rage), and demonstrates it on a few occasions. But it seems to be a secondary feature of Conan's, not a regular and defining one.
I think Class-based games may have taken niche protection too far and it has devolved into cliches. Which brings to mind an idea for a different thread.