I think there's a fairly high "Disregard the stats and 'just roleplay'" attitude among players I would broadly characterize as the "grumpy old fart 'it's roleplaying not roll-playing'" crowd. And those also tend to be the people most likely to tout "Just roll 3d6 in order as the almighty Gygax decreed!"
Which is much easier when that has nothing at all to do with how well your character can do at 2 of the game's 3 modes.
Sometimes even the combat pillar. A Basic Magic User uses intelligence simply to determine whether they get a bonus to xp for high int. A comparatively dim MU of level x can mechanically cast just as powerful a fireball as a super sharp MU of level x.
There has been diversity in how people do most everything in D&D since the very beginning, but OD&D, original 1e AD&D and the Basic D&D lines all had random stat generation with little customization options and very little mechanics on the mental stats. Bonus xp if the class prime requisite was really high (comparatively rare on 3d6), and things like bonus languages or reaction adjustment and max # of henchmen. Most of the exploration and social pillars were not RAW stat influenced.
Late 1e (post Unearthed Arcana, starting with Oriental Adventures) developed non weapon proficiencies with mechanics sometimes tied to stats.
Role playing was mostly first person roleplaying and figuring stuff out was the player as the character figuring stuff out. People would look at the PC stats and either say the minimal mechanics were the end of it or they would extrapolate that these were the guides for the character and freeform off of that with no other guidance. Similar to alignment there have been people going with you should work off the sheet, and people who don't.
AD&D introduced some choice in certain of the stat generation methods, first in some options in the DMG (stuff like roll up six sets of stats and pick the one you like best, or some where you got to assign which stats rolls went to), then big ones in pick your class first Unearthed Arcana human roll options with lots of dice, then in 2e's options including a point buy one.
When it is 3d6 in order the numbers are going to generally be not high and random for what is good or bad on any character.
In stat choice systems and particularly in point buy there is more of an argument about having chosen to play a high mental stat character or not, but the incentives to create a stat build for synergy with a class increases which will specialize high mental stats to mental stat based classes.