I've been stewing on this for a while, and I still don't know the best way to articulate it. But here goes anyway.
If you're expecting 5e to have every PC as good as every other PC in every pillar, then you'll be disappointed. It doesn't do that, and has been designed to specifically not do that.
That's a good way to articulate it. The issue with the fighter, for instance, is very real. It's just also intentional.
5e seems to be designed to have it as a team sport, so-to-speak, as the default mode of play.
4e was designed that way. You had positions (formal Roles) on the team and everything, characters where all on the field at once, all contributing, and even synergized a little. 3.5 had the idea of iconic class roles, that "a fighter" was a necessary part of the team, for instance, but that a Barabarian or Paladin could fill in for one, an idea that was preceded/suggested in 2e with the 4 class groups, and in 1e with the way sub-classes were grouped under the Fighter, Cleric, Magic-User and Thief. 3.5 also added the idea of a '5th wheel' class (Monk or Bard) that couldn't quite fill in for an iconic role, but could be nice to have when the other roles were filled.
5e is more like an all-star exhibition of different sports. Each character does his thing really well, when it's his turn to go out and show off, it's up to the choreographer to decide the order the go out in and the relative time spent on each. There are no formal or even iconic roles and there aren't 4 class groups or 4 primary classes with a few sub-classes each that can maybe fill in for eachother - there are a dozen classes and 38 sub-classes, and most get to be happily unique in some way. In some cases, one class can replace another - a Barbarian or Paladin could stand in for a fighter pretty well. In others, it's not so clear - can a Bard replace a Cleric or a Warlock a Wizard? - maybe, sorta. Then there's classes that seem to be able to fill in anywhere: a Druid could assume a melee form and fill in for a front-liner, cast offensive spells like a wizard, heal like a cleric, or assume a small/inconspicuous form and scout around like a rogue. Maybe that last isn't as bad as it was in 3e, but it's still there.
What 5e does do, and does very well between skills, backgrounds, feats, and bounded accuracy, is give players a lot of choice.
Not so much, no. It doesn't hold a candle to 3.x/Pathfinder in that regard, for instance. Bounded Accuracy, for instance, shifts the effect of investing in a skill 'against type' from 3.x "it doesn't matter because the specialist is /soooo/ much better than you" to Bounded Accuracy "it doesn't matter because you already had a shot anyway, and so does everyone else."
Rogues and Bards have a little more choice because they can take Expertise in /anything/, though, which is kinda fun for them.
You can choose to be good at pretty much everything but not be super good at one thing. Or you can choose to be super good at one thing, but not super good at everything else.
Bounded Accuracy means you can't really choose to be super-good at anything (again, unless you get Expertise). You can be pretty good, or not so bad as to be hopeless, or just OK.
If you're looking to be super good at everything, or to have no other PC better than you in any of the pillars? 5e is not for you.
With big enough gap in system mastery between you and the next guy, you could probably pull it off. It'd involve some near-prescience and tight resource management. Or, of course, just getting the DM on your side.
That's not an attack on your senses or players who prefer that. It's simply stating how I feel the game was designed.
Nod. While 5e tried as much as possible to be 'all D&Ds to all D&Ders,' it prioritized capturing the classic feel of D&D over that inclusiveness, so there were, ultimately, more than a few styles that aren't supported by the game. It is, though, DM-empowering enough that any DM determined to could make it support any style he wanted it to.
Upthread I read someone say, "why bother bringing the fighter along then". Well, the game assumes that at some point you'll be doing what the fighter does better than everyone else.
Yeah, well, that's where it starts to fall apart. The fighter is really, really combat focused, he doesn't have a single class feature that isn't useable in combat, and vanishingly few and minor features that are expressly useable out of combat. But what it gets for that focus is an AC maybe a point higher than the next character who's player really cared about AC, not-quite-as-high hps as the Barbarian, and DPR that's consistently high, but that some classes are competitive with, and just about any other class can reach at least some of the time.
And I will fully admit my biases when I say that I think it's a huge mistake and goes against the spirit of the game to either have the impression or to try to argue the impression that unless you are the best at something in your group, you shouldn't be doing it. This is a feeling I get a lot whenever I hear people imply or infer that PC X shouldn't attempt task A because PC Y is better. Or that PC X can't do tasks A, B, or C because they are specialized in only task D.
Sure, when it comes to skill checks or killing a monster, thanks to Bounded Accuracy, anyone and everyone can & should pile on. But when it comes to what each character brings to the party (npi), the fighter could be judged wanting. A fighter brings DPR, which every class also brings to varying degrees, personal durability, which some classes meet or beat, and nothing else, which every other class beats.
5e gives you the choice to build a fighter who is very competent in all three pillars.
The fighter is hardwired to be at it's most competent in the Combat Pillar, and, within that pillar, at single-target DPR via multiple attacks. There's just no way around it. Multiple attacks are effective for generation DPR in D&D, to the point of being problematic, and they're non-negotiable.
You can build a fighter who is really not that bad in the other two pillars, because any warm body (straight 10 stats, no proficiencies) is, thanks to Bounded Accuracy, really not that bad at any check, and checks apply in all pillars. In fact, you can't avoid doing that with any class, it's the base-line. Backgrounds will make you competent at another couple skills and maybe the perk will come up once in a while. But, again, that's just part of the base-line, every PC has their Background.
But to really put that 'very' in front of competent, you need to have something more than an ordinary skill check to contribute - Expertise, or a special ability, or an applicable limited resource, or whatever.
But, as we established, above, that's all intentional.
It's not, "wow, WotC really screwed up designing 5e because the fighter is a lame all-combat beatstick,"
it's "wow, WotC did an exemplary job designing 5e, because it feels just like classic D&D, when the fighter was a bad-ass all-combat beatstick."
What it comes down to is that, in 5e, if you want a certain kind of play experience, you are limited to certain archetypes, and if you want to avoid a certain kind of play experience, you must, obviously, avoid certain archetypes.