520 , 10 months ago

You'd be surprised how hard the task is. Any given identifier can be trivially changed. IP addresses aren't permanent and change frequently for home users. Multiple people genuinely use the same IP. People are likely to have very similar writing styles to someone else by complete coincidence. Browser fingerprinting can be thrown off by simply using another browser or fucking with the User Agent.

That about puts paid to any identifiers either Reddit or an instance owner may have.