One upon a time, before Feats and Skills allowed characters to specialize and focus, putting together a Fighter of level X was 10 minutes with dice and a piece of paper. You rolled the stats, picked a race and bought equipment.
If you were playing 1e you might pick a "profession". (I had an idiot Dwarf whose profession, randomly rolled, was Limner/Scribe". Having an 8 Intelligence, this Scribe couldn't read or write. Had a lot of laughs with that one.)
If you were playing 2e you had "Non-combat proficiency" options, but that was it. 10 minutes and you were done, probably with 5 minutes left over to get a cup of coffee.
In those earlier editions the Fighter was a generic thing. Pole arm, battle axe, long sword, great sword, long bow or short, he was equally good with them all. If you happened to roll really high on Dex he's be a better archer, but was otherwise pretty much interchangeable with any other Fighter of similar race.
In those days it was accepted that the Fighter's job was, at least in part, to protect the spell-casting artillery, to be literally a meat-shield. Spell casters were very breakable, particularly at lower levels. (Any damage in the round fizzled your spell, no Concentration to keep it, no "Casting defensively", and they didn't have to wait to strike while you were casting. Oh, and no bonus spell slots from high stats, and no free conversion to healing slepps for clerics.)
In the early days, published modules were almost always "dungeons", or as we'd say it, dungeon crawls. In town or overland adventures were too unstructured, the rules weren't set up to handle them very well. (That's when you had a "caller" and a "mapper". If the party splits up, how can the Caller tell the DM what the whole party is doing? How can the Mapper map two or three places at once? )
Under these highly structured, may I say "rigid", circumstances, party roles and behavior were equally structured and rigid.
Then came the "splat books" with specializations and goodies for almost everyone, loosening the rigid structure, and allowing player style loosened up as well.
Up until that moment the whole system and game mentality revolved around the nuclear party, indivible. It used to be, "If you wander away from the group, the DM just declares your character dead, and the main group moves on." Nobody sent out a scout, for the most part, because only Rangers had a chance to avoid a surprise (1 chance in 8), and they couldn't find Traps. Only Thieves could do that.
By the time 3rd hit the scene, the world had changed (and I'm not just talking Greyhawk to Faerun".
"Stupid" was now survivable, and the "one character party" was a lot easier to achieve.