an information that already exists (and is public).
It is not public. That is my point. (It is not even known to the developer running a web game!)
You do not see who is playing a game. You do not see who is online. You do not have a "friends" list. You cannot comment on reviews, you cannot even see them attached to a game. You cannot "share" your activties. Best you can do is publish a collection on your profile.
Would you call all message boards "social networks"? There are reviews with comments on products on online stores. You call those a social network too? There is a social component, yes, but that does not make it a social network.
Making information public that previously was not, is a thing that should be thoroughliy scrutinized. And imho unless Itch does implement a whole lot of other mulitiplayer support, there is no need to access such information for things like leaderboard that can be implemented by other means.