Lemmy admin should add option in the account settings for hiding your username from your posts/comments, and hiding your profile from the public, so noone would be able to see all of your posts in your profile page, and even if someone is using a tool for scrapping posts, they wouldn’t be able to link the posts to 1 user, because the username would be greyed out “anonymous” (and would not link to anywhere). Only lemmy staff would know the real username.
I hear what you’re saying, but you’re essentially aiming for it 4chan. Lemmy is very much a social media network with emphasis on social. We are a community, you can’t build a community without being accountable and that happens with post history.
That said, the suggestion to have member only profile pages is a cool one. It wouldn’t stop anyone from searching for your username and finding your posts that way, but it would make it just a little bit harder for them.
Is 4chan as private and secure as lemmy? I never used it.
secure: only if https used, default on most board
private: there are no profile or username, everyone anonymous