Yeah, it really feels like a new kind of forum.
Before I used forums to discover topics of interest, then the same thing was possible on reddit, lots of micro communities centered around a subject, no need to host your forum anymore, well now reddit showed its ugly face and lemmy seems a nice replacement
A problem I often see is with profiling from your data, imagine in a matter of three months you searched in google "remedies for headaches", "what causes stomach pains", "blood in feces", your profile might get a flag warning possible colon cancer, now the next year your health insurance rises to double, because of the possibility of you developing cancer.
This is just a single cenario where they collect info about you and profile you and then sell the data to insurance companies, insurance pays big time because this info is valuable to them. How do you feel about this and what other cenarios can you imagine where your profile could fuck you up?