I don't want to share my spam email with all my friends to get them to share with me. And I don't want to give my primary email to an app that will spam me.
If I want to share something, I'll send a link and the recipient can connect to me that way. I don't need to search them within the app to get in contact, that's useless.
> so when they enter your email address, our systems will believe that you don’t have an account. At that point, you’ll get an email from us asking you to create an account.
This is a trivial part of the problem to solve. Why am I being asked to create an account in an invite email? Why not "log in or create account" and having the link itself be the piece that connects the share to me.
It's dead clear that you don't work with consumers. Your technical bias shows what you care about and you're(an me) are an utter minority.
If you want security, btw - you should have multiple passwords for different things. And ideally not even use a password manager.
Still, I think in this day and age, having a requirement in your product that says "e-mail that is provided should be the one the user uses the most" is pretty naive. In general, it's true, but when it comes to 3rd party authentication providers like Facebook, Google, and now Apple, this kind of requirement is not really useful and will likely cause issues for you down the line, which is why usernames are better for addressing people within apps (e.g, Instagram handles).
Riot does this with Valorant too and the implementation is a nightmare.