I would like to know your definition of "typical group". On a Pick-up or matchmade group, unless there is an express purpose of "messing around" or some such, I expect everyone to damn well bring their A-game. And when that A-game is sitting on their super until they needlessly die and immediately res, then no, they're not halfway competent.
I fail to see how a res on the Bridge does anything more than save half a minute waiting for the revive timer while stepping off the plate and dodging adds (this applies to NM, on HM FB is okay, and I feel quite a few people actually expect that of Warlocks, going by the reactions I get for being Voidwalker.)
I was never talking about a group's competence, but only about singular members'. Mistakes are natural and unavoidable, but more skill or experience can help reduce or mitigate them. A halfway competent group doesn't need anyone resurrecting, because deaths should be rare enough that the rest of the group can carry on with one less person for 30 seconds.
Also keep in mind that what I'm writing is general advice for playing with randoms or mixed groups. The specific situation supersedes that, obviously. If you're just messing around with some friends, I'm hardly gonna tell you what to do. Similarly first-time raids and being underleveled are arguments for running self-res too. But generally speaking, FB negatively impacts peoples' playstyle and stops them from improving as much as they could.
I'm speaking from experience there. When I was newer to the game, for a few weeks I ran FB exclusively, and had a bunch of needless deaths when my super wasn't up or when playing my Hunter or Titan. I always went "I'd have needed my self-res there". Idk if I just stopped to think about it, or someone pointed me in the right direction, but once I stopped leaning on the crutch that is Fireborn after a short period of acclimatization (plus Xur selling the Obsidian Mind getting me more into Voidbro) I could confidently say I became a better player. I both did more damage and had less deaths, and am now at the point I can manage to do an entire raid or Nightfall without dying (barring mechanical or intentional wipes, in the former case).
I may have some rather high standards as for what constitutes "competence", but I won't hold anyone to anything I don't hold myself too, so I don't think I'm being unreasonable.
In closing, Fireborn may be useful as a support for newer/weaker/learning players, but just like an actual crutch, if you keep leaning on it, you won't get any better after you hit a certain point. And I believe hitting and recognizing that point, and casting the crutches aside to aspire to new heights is what truly marks a "good" or "competent" player.