Social media presence as in having accounts in your name with you being visible in the profile picture in mainstream sites (Anything Meta, Twitter, Snapchat, Tiktok…). I don’t consider anynounmous accounts on Lemmy, Reddit, Kbin relevant to the scope of this question.
Aren’t Lemmy, kbin, Reddit etc. just web forums?
Social media is a very specific type of product that (at least partially) tries to base itself on your ‘real’ social life.