Tolerable levels is subjective. The point is, people want to be able to play the concepts that interest them without being at a disadvantage compared to people who played more “traditional” concepts.
it's a hard line to parse though. If character A is just as good as character B in combat but much more versatile... why play B?
Is a charismatic fighter significantly more versatile than a strong fighter? If so, seems like a problem that could do with addressing. Perhaps strength is lacking in versatility.
I would presume based upon the three posts you both made that Ancalagon was under the impression that in order for a person to play a fighter that "interested" them that was
not at a disadvantage against a traditional fighter meant that both fighters had equal levels of standard fighter abilities (STR, DEX, CON) while the "interesting" fighter also had a high CHA (or whatever it was that made it "interesting".) And in that regard... then yes, if the "interesting" fighter was equal to a traditional fighter
and got to raise a mental stat really high... then there would be no reason to play a traditional fighter.
But that's just not doable. If you take Standard or Point Buy into account when creating your PC... you can't give a fighter a high mental stat while also being equal in physical stats. You have to sacrifice at least one of the physical stats by a point or two in order to bump your mental one.
Although really... how big of a sacrifice are we talking here? If you wanted to make a charismatic fighter and even with using Standard Array (15, 14, 13, 12, 10, 8)... you put put your +1 in STR and your +2 in CHA and you can get a PC that is STR 16 / DEX 13 / CON 14 / INT 8 / WIS 10 / CHA 14. There is absolutely nothing wrong with this character. Unless of course the player is going to complain about being a point or two lower on WIS saves than they might otherwise want to be. But that's then the player putting game mechanics ahead of character concept-- wanting their cake and eating it too. But in that regard that's just too bad... there's no requirement that says every PC is to be fully up on all possible defenses against all possible attacks while also having their creative "interesting" abilities as well.
You want a charismatic fighter... you might have to be less intelligent and/or be 5 or 10% worse on WIS saves than your traditional fighter build might be. Or maybe have your WIS boosted too, but have no DEX. It's all choices. But there's no fighter out there that will be strong, charismatic,
and have really good DEX / CON / WIS saves... unless the DM has PCs roll for ability scores and the player lucks out.