1 more benefit of different pseudo-emails for each service is that when large collections of email, passwords are leaked then hackers can't apply same email to different services as each service would have a different account. This could safeguard users from situations like the recent Collection 1 leaks. I think you should list this as a benefit. Though if I make amazon-myname@kobi, twitter-myname@kobi then hackers can obviously try to guess the email, but still would be more work for them.
Basically, in 1 sentence, the benefit is that, till now, aware users followed the obvious rule of different passwords for each service and then use a password manager to manage all. But, a much better norm would be different email AND password for each service. this part is important: DIFFERENT EMAIL AND PASSWORD. I want this to become a norm in the next 1 year. By norm, I mean I want some big players to implement this as well. Also, good work on kopi. What are your thought on bulc.club ?