Email isn't only successful just because network effect. In fact if it wasn't really good already, it would have been replaced at least partially by phone numbers, which is not only earlier than emails, but also more prominent in chat apps which are increasingly more prominent in commerce and many other access context where you join the thing just by joining a group chat.

I am singing the praise of reliable and simple messaging, whether that is reliable messaging of a server with TCP/HTTP or a more intermittent entity like the case in Email, and indeed SMS or other chat apps.

Email is indeed benefiting from network effect, but it is also not the first solution, it was just the first good enough solution. And indeed any upgrades that I find worthwhile for Email, happen entirely at the DNS level, not the email format or protocol.. that shit is really truly good enough...

Hell I am using a Signal alternative that is entirely on Email protocol and it is working like a charm, and it is not even using Email as a thing you already have, it creates whole new account in the background... It just uses SMTP because SMTP is simply good enough