After having tried the Arc browser for just a day and no longer using it, here is my conclusion:

1. Don't have time to learn new browser behavior, even if it's better

2. Didn't feel like I was missing anything after closing it, no urge to re-open.

3. Password management is a pain and I don't want to get it working on a new browser.

I think it's tough remaking something people are so used to.

If I had to draw some parallels between browsers and nostr, I'd say the password hurdle (lack of a reset function and just learning what keys are) might be a blocker for many. Not saying they won't learn, but it could be an issue for a bunch of people who'd rather not bother.