I tried to limit as much as possible switching between email addresses.

Because of there is no central authority to bind an email to a person, you cannot really ever delete an address.

I used to have a gmail address, and then I switched to a custom domain + email provider when I started to want some emancipation from Google. My gmail address still exists but redirects emails to my new address. I refrained from creating aliases to that address for the very reason that I wouldn’t be able to delete them.