Depends if all those devices play by the rules properly, when requesting band-width.
…or, let’s say (as a hypothetical), 3 devices audio were requesting 30 percent each and some ofher device were requesting 11%.
It’s possible that without a QOS mechanism being strict, that most of the time, even though a certain amount was being requested, those devices would actually work OK together, most of the time - given tolerances and balancing.
…but a more strict QOS system might reject one of them.
All hypothetical though and it entirely depends on each system and what’s connected to it. I don’t know what changed, but what I’m saying is - it’s not necessarily Apple having “broken” something. They may be forcing compliance.