It's a client (several), it allows other clients, and it does the SMTP, POP3 and IMAP thing. It filters spam and sorts things into enumerated named folders, and you can download everything and store everything as mbox files with attachments in a big-old folder, and still be able to locally elastic-search it all, or leave it on Google's servers and search through their web UI. Isn't that email-ey enough? If not, what's it missing?
I'm quite happy with Gmail... It doesn't have any of the negatives listed above.
Sure, it was not acquired by some super-evil corp but it was created and owned by one instead. That seems even worse (especially when considering that google was not evil in its early days, or at it was not widely known).
It is also willing to lock you out of your account and keep begging for your phone number (even if you haven't entered it previously) in order to unlock it.