Most plug-ins are available as multiple formats though. Is it really that much of a friction point?

Pro Tools has seen huge success despite being the only major user of RTAS/AAX for example.

The part where they're not available on mobile? Incredibly so.

The fact that there's no AU on Windows? Less so.

Yeah on the apple its Au only but with the clap plugin format its open source so it may be possible to have clap plugins in an android daw, but on ios its au only and I doubt that will change.