"There aren’t many downsides to #nostr growth being tied to #bitcoin"

Yes there is. There's a very strong possibility that p2p communications combined with p2p monetization will form centralized siloed communities governed by Confirmation Bias.

This could lead to information poor spaces between silos and narrow cult thinking becoming dominant.

Notice the information centralization on Bitcoin Twitter.
We have "freedom maximalists" and/or "Bitcoin maximalists" pushing keto, non seed oil, austrian and ancap bs economics, as if they are club entry requirements.
The same maxis that are suddenly silent with women losing sovereignty over their own bodies or have nothing to say about child deaths at school.

They built a monetized base for themselves by attracting similar minded people - now they are in thought prisons because to dare to be different means less income for their centralized social media business model.

I'm all for decentralized networks and their promise of free and open communication but lets not kid ourselves of the possible hazards and unforseen outcomes