Also, note: in theory MusicBrainz already has metrics for the number of clicks, views, lookups, and edits certain entities get through their site and API. I bet these are strongly correlated with listens/popularity.
What does "in theory" mean here? Do those tables exist in whole or some part? Is this a matter of indexing an existing data set or hoping some data was acquired by accidental consequence?
Even if it's not collected though, it's data that they at least already have the ability to collect by simply flipping a switch, as opposed to spinning up a whole new ListenBrainz service and hoping it gains traction.