What broken really means when used properly is breaks the game.
Meh. You can change definitions in the middle of the discussion if you want. It's pretty clear from the way it's been used all these pages that it's about the feats being too powerful or too abuseable, rather than non-functional or game-breaking. An example of 'broken' in the non-functional sense from 4e (since you're already picking on it), would be the original skill challenge rules, that presented 'complexity' as a measure of how hard SCs were and how much exp they were worth, but which actually worked out to more complex challenges being more likely to end in success. That's a non-functional 'broken' rather than an OP/abuseable 'broken.'
One of the only examples I can think of was the 4e math where the +s broke down at higher levels.
They deviated from the implied 'treadmill' progression. That was a real thing, but it didn't really break the game - high-level characters had so many additional resources, they could do fine in spite of theoretically falling behind the curve. Didn't matter to the chorus of complainers, though, so...
They introduced the feats to give +s to fix it, but those became a feat tax so it wasn't really a fix at all.
The 'expertise' feats are a good example from 4e of feats like GWM/SS - too powerful compared to the alternatives. Maybe they arguably were meant to serve a purpose - shore up a weak class or build or whatever, or smooth the PC's power curve as they level or something, but they ended up sticking out from among the other feat choices. Ironically, some DMs would ban them.
Martial characters not focused on DPR contribute plenty to a team.
As long as we're quibbling about definitions (see immediately above), if we take 'martial' to mean 'uses martial weapons,' sure - a Paladin, for instance, has significant features and casting to contribute in a support role, even if he doesn't optimize for DPR and never smites, he can still be helping out the team in significant ways. If we take 'plenty to contribute' as including the simple feature of Bounded Accuracy that basically anyone, even checking at -1, might succeed on just about any check that anyone else might fail on (even if only on a really bad roll), and thus is contributing anytime checks are called for, again, sure, no doubt about it.
Honestly, it's not about not minding or reveling in its brokeness, I don't see it as being broken at all.
IDK, 'is not broken all the time' the same as 'not broken at all?' (whatever the definition of broken) I don't think so. Not minding, not seeing, not noticing, not caring - however you want to put it, it's perfectly reasonable and plausible, and in no way contradicts the thing in question actually
being broken having quantifiable issues.
. It's when you start stacking advantage, precise attack, bardic inspiration, bless, et al that the feat "breaks". That's not a broken feat in my book. It's simply a broken combo.
If you want to share out the 'blame' like that, it'd be fine as far as it goes. You open up more ways to 'fix' the issue, if nothing else.
If your players aren't the kinds of people to exploit that combo, then nothing about it is broken in your game.
Sure, in the sense that a stopped clock is right twice a day or a car that doesn't run works fine as long as you never need to go anywhere. It's a very practical sense, really.
Maybe, if folks keep stressing out over this feat the WotC team will actually errata it. .
I'm surprised WotC has issued any errata at all. When you present your system as a 'starting point' It's going to be changed, anyway.