I don’t think you having to either A) remember what email you used or B) creating a new account is a big ask when the alternative is leaking your account presence on a given system. Not everyone wants other people to be able to essentially query a given app for an email account.
Monitor having issues. Google solution. Land on a forum, but to see the full post / solution it requires email registration. I register with a junk yahoo type email address. Complete the long form, solve all the traffic lights, etc. Then get the solution, make a few posts and probably forget about it.
Monitor having problem again after 2 years same forum but it says my very unique username is taken. Now, I vaguely remember creating an account but don't remember what email I used. I try to reset my password but dang, each time it says "If that email was in our db you'll get it". If I get a hint I used yahoo maybe I can resume and hopefully use my old account and some post count than starting a 1 day old account with 0 post.
So your idea is to always gives malicious actors additional information for account take overs so you can use an account with a non zero post count (not just non-zero, but only 1 or 2 as you insinuated)? Do you not see how naive that is?