I'm sure this has already existed for years. The AI technology needed to implement this has exited for years. You just need to do web crawling and keyword and l

I'm sure this has already existed for years. The AI technology needed to implement this has exited for years. You just need to do web crawling and keyword and link matching. You don't even need a 'writing fingerprint', you just need to parse comments which reveal identifying information such as 'I participated in project x', 'I taught at university y', 'I invested in startup z'... then when you combine all the identifying information, you can narrow down the pool of possible matches to a single person. You could probably do it with just basic text matching, no AI required.