> [...] I think they do this so they can retain users.

They lost me as a potential user within the first 10 seconds and I'm probably not the exception here. No idea how you want to retain users if you lose them before they even get to test your software.

> To be fair, as an Arc user, by logging in, I can keep my tabs synced perfectly across my personal and work laptops, which is worth it for me.

I can do that with Firefox, Chrome, Brave or any other browser as well without being forced to create an account.