I would actually consider making a collaboration novel at lot more work than a writing workshop or anthology, because of the greater team cohesion required.
I haven't been part of any serious writing workshops, but the casual ones I've joined have been much more about encouraging people to keep writing, swapping tips about editing and methods of publication, and making other writer friends. (We did have people working on very different types of stories, so that might've made people feel less like it was a competition though.)
On the other hand, co-writing takes a lot of trust in the other people working on it. You have to be on the same page for genre, pacing, characterization, tone, mood, and overall plot points. Each additional writer is an added factor to figure out, an extra potential ego unwilling to compromise with the other writers.
Most successful co-writes are between smaller groups of people who know each other well for that reason, although if you get some good organization in place, it could be an interesting experience.
I'd probably be down to try one massive google-doc + Discord VC collab novel attempt though, for the experience if nothing else. Though there'd have to be some good rules and moderation in place.