It really depends on the kind of game.In all my years of gaming one player having great stats has never caused an issue, and has never been the key for a character dominating the game. My players always seem to view anything that makes the group stronger as a good thing, and intelligent play and good luck is far more crucial to a PC and party survival than a few additional points of bonuses IME.
In a lot of games, party success is (mostly) a given. The players always win unless they do something really stupid, and the DM's job is seen, in part, as tweaking the goalposts to keep it that way. So anything that makes a group stronger is, ultimately, irrelevant, because the only question is, "which character (or maybe 2) will die before we finish the campaign?" I'm trying to move my game away from that mindset, but I really think it is the assumption in the mainstream game as published and played over at least the last decade or two, if not longer.
So, under those circumstances, if one player makes the group stronger, nobody notices, because the group always wins. But they do notice that that one player sticks out a little more. And, even if your players are all pretty mature about it and not bragging about their damage output all night, it changes things up for the DM. Challenging one player destroys the other PCs, like trying to teach math to a class with one physicist-to-be and a bunch of artists. (I know lots of artists who are great at math, but, whatever.)
And, while I don't want to play the game that way, the reality is that a lot of us do play the game that way, and plenty of people want to play the game that way. And rolled ability scores, with the power level disparity that that brings (especially when it comes to choosing feats instead of ASIs), can make that kind of play harder. The standard array, on the other hand, does nothing to jeopardize a gnarly, old-school style of play. Those characters are not natural-born munchkins. They have built-in weaknesses. Even a fully optimized point-buy character is still going to have one 12 where another character had an 11. Or maybe 3 decent strengths and 3 weaknesses. (If you go for the 15, 15, 15, 8, 8, 8 array.)
I love random, and I love the idea of "playing what you roll," and I love the idea of playing a suboptimal character against long odds (and possibly failing), but that's not how most people use the rolled abilities anyway. We don't play what we roll: we can reassign our abilities to whichever stat we want. We don't play sub-optimal characters, because even the official method generates, on average, better arrays than the point buy, and most tables have some sort of system, official or under-the-table, in place for helping out the truly skunked random arrays.