Complaints about LFQW are complaints about how much narrative power each class has over the game.
No, LFQW (linear fighters, quadratic wizards) specifically refers to the fact that in 3e (and maybe earlier editions to a lesser degree), wizards got more spells AND their existing spells got more powerful whenever they leveled up: thus, their power increased at a "quadratic" (geometric, exponential) rate. Fighters, on the other hand, got more powerful too, but at a linear rate. So a level 20 fighter might be 20x as powerful as a level 1 fighter, but a level 20 wizard was 20^2=400 times as powerful as a level 1 wizard. (Or so goes the argument; obviously the math for "class power" isn't that simple.)
In other words, LFQW was a problem even when comparing "blaster" wizards (who only prepared tactical spells like Fireball and Magic Missile) to fighters. Wizards' non-nuking abilities, like teleport and scry and invisibility and so on, were a separate issue.
In 5e they've mostly fixed LFQW by making it so spells don't scale with caster level: a level 20 wizard in 5e has more powerful high-level spells than a level 1 wizard, but his level 1 spells are just as weak as ever. And it certainly doesn't hurt that they've upped the fighter's damage scaling while they were at it.
But that still leaves the disparity between classes in their out-of-combat utility as an issue, which is what this thread is about.
As I've already said, I think rogues in 5e are actually fairly well-balanced in exploration and social challenges; the reason fighters (and possibly other martial classes) aren't is that for some reason WOTC designed an entire system to govern non-magical utility, the skill system, and then declared that rogues had to be "the best" at it. This almost by definition makes other martial classes suck compared to rogues outside of combat. Plus, it doesn't make a whole lot of sense for non-roguish skills- why would a rogue be better than a fighter at climbing or riding or diplomacy or medicine, if both have "trained" in them? But I guess this is a sacred cow or something? Bleh.