What's the point of creating aliases if companies already have my original email?

Guys I'm really sorry if this has been asked before. I tried looking for an answer, couldn't find anything similar on reddit.

So I've been using a dual-mail system (PM as primary email for casual purposes. Tutanota for work, banking and more sensitive purposes.) Now I'm thinking of deleting Tutanota and shifting completely to PM, create a new account and use Anonaddy for aliases. But does it make any sense? Removing my primary email and using aliases instead? Especially since …

companies email privacy