Unfortunately if you don't start out using that, then your email address is already spread across the web. And back when I was looking at gitlab/bitbucket/etc for feature comparison, each forge used their own domain and couldn't be persuaded to combine commits from multiple addresses into your own profile (to be clear, that's not really necessary, but it does make it more difficult to find a commit created by someone when their commit address isn't the address associated with their account)