I don't think Dungeons and Dragons should allow for everyone to be equally competent in everything. That's not its design strength and what the narrative paradigm its core original design has been based off of.
While no one should ever be completely deficient in one of these three pillars as they have been described, having strengths and weaknesses is a core DnD concept. I'm not sure why people are so quick to rush to the Fighter as an example of someone who cannot socially interact for example. If you think about a fighter for a moment consider this; fighters roam the world searching for adventure and treasure. As a result a seasoned fighter should be at least somewhat world-wise. They've certainly left the lands of their birth if they haven't left their motherland outright. On the way they would have had to have learned at least a little about the different cultures they passed through and they tend to associate with the masses. If we consider the average stereotypical image of a fighter, being the kind of man who likes to frequent bars and taverns then they could even have a pulse on the troubles of the commonfolk and even hear bits of politics. How much more social exposure does the Rogue or Thief really have? They might spend more time in these places than the fighter, if they are the sort of rogue that pick-pockets and scams as opposed to the sort of rogue that goes along with the fighter into those dungeons and lairs. Aragorn was fairly charismatic and was able to talk easily with various people, Barak from the Belgariad as well lacks the same kind of upbringing but can talk to people and is formidable in combat. There are as many "fighter" archetype characters from literature which are equally competent outside of the combat arena as they are within it.
There's no reason why a Fighter cannot be thematically as competent at social interaction as any other character. (I needed to sign up just to get that off of my chest actually
) Wizards are usually considered to spend more time poring over tomes and conversing with alien or Planar creatures. Why are they considered to be better at social activities when that same stereotype spends their time being antisocial?!? Nor are Barbarians or Druids not equally as useful and able to contribute in an urban game. Druids have a strong relationship with Animals and often at higher power levels the ability to commune with them and shapeshift. Cats and dogs are common in large towns and cities, so no one is likely to notice an extra one for a few hours or so. The other animals around them might have all kinds of useful information that more 'urban themed' classes might have. A Barbarian might be able to provide the group with different viewpoints, or even speak with slaves in the city. They can do things like lift sedans and move cargo to fit in and keep their ears out. Beyond innate abilities such as magic or Rage the only limiting factor to how a character can interact is how imaginative the GM and players are. I've played a martial artist in a game set in a city of mages and still meaningfully contributed without any particular investment into social skills. It turns out climbing and acrobatics can be handy getting in and out of places when buildings are really close together!
So I'd challenge people to think carefully about whether these stereotypes in Dungeons and Dragons gaming are really flaws in the system, or crutches that have come about because of player preconceptions. Cross-class skills from 3rd Edition were...not great in my opinion and I think Pathfinder handles skills a little more streamlined but the framework is much the same. It's an area which could use work, but I cannot really think of recent editions that have really prevented anyone from investing outside of the standard stereotype conventions of a class. It has usually just been at the cost of specialisation, be it in combat or not. But then again if your character is entirely focussed on squezing out the most damage or spells as possible then perhaps that lack of social grace is appropriate for the way they are played.
All that said and done, I would like to pose to the designers of 5th Edition this thought; if you want exploration and interaction to have equal weight in a game, then should they not also have similar diversity and opportunity for advancement as combat? The last two editions have been based largely on combat in terms of supplement materials. Even the core materials have had lengthy chapters on combat oriented material in comparison to a mere one or two on non-combat interactions. If these three pillars truly are a new paradigm, then perhaps they should have equal development and opportunities for the characters mechanically and not just at the GM's discretion.
While no one should ever be completely deficient in one of these three pillars as they have been described, having strengths and weaknesses is a core DnD concept. I'm not sure why people are so quick to rush to the Fighter as an example of someone who cannot socially interact for example. If you think about a fighter for a moment consider this; fighters roam the world searching for adventure and treasure. As a result a seasoned fighter should be at least somewhat world-wise. They've certainly left the lands of their birth if they haven't left their motherland outright. On the way they would have had to have learned at least a little about the different cultures they passed through and they tend to associate with the masses. If we consider the average stereotypical image of a fighter, being the kind of man who likes to frequent bars and taverns then they could even have a pulse on the troubles of the commonfolk and even hear bits of politics. How much more social exposure does the Rogue or Thief really have? They might spend more time in these places than the fighter, if they are the sort of rogue that pick-pockets and scams as opposed to the sort of rogue that goes along with the fighter into those dungeons and lairs. Aragorn was fairly charismatic and was able to talk easily with various people, Barak from the Belgariad as well lacks the same kind of upbringing but can talk to people and is formidable in combat. There are as many "fighter" archetype characters from literature which are equally competent outside of the combat arena as they are within it.
There's no reason why a Fighter cannot be thematically as competent at social interaction as any other character. (I needed to sign up just to get that off of my chest actually

So I'd challenge people to think carefully about whether these stereotypes in Dungeons and Dragons gaming are really flaws in the system, or crutches that have come about because of player preconceptions. Cross-class skills from 3rd Edition were...not great in my opinion and I think Pathfinder handles skills a little more streamlined but the framework is much the same. It's an area which could use work, but I cannot really think of recent editions that have really prevented anyone from investing outside of the standard stereotype conventions of a class. It has usually just been at the cost of specialisation, be it in combat or not. But then again if your character is entirely focussed on squezing out the most damage or spells as possible then perhaps that lack of social grace is appropriate for the way they are played.
All that said and done, I would like to pose to the designers of 5th Edition this thought; if you want exploration and interaction to have equal weight in a game, then should they not also have similar diversity and opportunity for advancement as combat? The last two editions have been based largely on combat in terms of supplement materials. Even the core materials have had lengthy chapters on combat oriented material in comparison to a mere one or two on non-combat interactions. If these three pillars truly are a new paradigm, then perhaps they should have equal development and opportunities for the characters mechanically and not just at the GM's discretion.