All good points...
I guess this kind of mirrors the discussion about Bitcoin adoption where people make the argument that, you have a "front-end" fiat, but on the backend it's BTC... (C.f. square terminal)
I fully believe that this strategy, similarly to Mastodon bridging, will lead towards people making the "paradigm shift" towards BTC and Nostr respectively.
Mastodon users will eventually come to appreciate the value of self-soverign identity, just like the vendor who can now accept BTC on their existing square terminal will inevitably see the value of self-soverign money.
At the same time, I love the eclectic little community culture of Nostr today. But if we really expect millions (billions?) of users, it's sort of inevitable that "Nostr culture" will go away just like "internet culture", which was a thing in the 90s, basically doesn't exist anymore...