Thank you for your many years of work on MusicBrainz.
I don't interpret things this way. I see that an ensemble is more than a collection of performers, it is an approach to artistic decision-making, it is a brand, it is an organisation with the purpose of making music, it is a business. Thus, saying an ensemble was involved in a recording is different than saying four individuals were involved in the recording.
For example, there are a set of five musicians in my town who perform as both a new-music ensemble Standing Wave and as members of the mainstream Vancouver Symphony Orchestra. When they show up to play, which ensemble they are part of for that performance affects their repertoire, their approach, and probably more.
You can imagine an extended MusicBrainz where relationships are transitive: if a relationship says that a string quartet performed on a certain date, and another relationship says that a certain violinist was a member of the group on a certain date, then MusicBrainz could deduce that the violinist was part of that performance. Except that this transitivity fails if an ensemble has a rotating stable of performers, and only some appear for each performance.
So, all this points to facts about music being complex, and MusicBrainz being a simplified representation of those facts. As a consequence, some facts have to be expressed in multiple ways, and some facts are hard to express. And our Style guidelines, even though they provide a lot of guidance and are the product of a lot of hard work, still need improving.
I probably would have voted against removing the ensemble AR from Edit #37627973, but I probably would not have made the effort to add the ensemble AR after having added the individual performer ARs. So I think there is room for reasonable people to disagree on the question.