[ignoramous]

> ask for a new feature that would take ages

You underestimate the level of cooperation that can exist between two tech companies working on each other's proprietary code-bases (where warranted). I'd wager that those agreements won't look too different than with source-available firms.

So, to me, there's no added benefit to source-available; some of these firms want to build a FOSS-like community but also don't want to be FOSS.