Facebook has a lot of topical groups where you likely don't know anyone anymore than you do here aside from they have expressed interest in a topic enough to join the same group as you.
Sure, but I don't think there's any particularly obvious reason why Facebook would be the place for a topical group to set up shop. I think it is a bad place for a topical group because you cannot read the posts without logging in.
If you're in the Facebook ecosystem maybe this is less visible. But if friends plan an event in a Facebook group they are excluding me and others who don't use Facebook for many valid but irrelevant reasons.
One such reason is that pseudo-anonymity is crucial for a lot of people for professional or personal reasons, and it's way easier to support that elsewhere.
Others include data privacy policies.
Maybe there's not a great choice that has the right blend of ease of access and ease of setup. But I think Facebook is demonstrably bad because of the requirements of logging in to read at all and to enforce that your profile has a real name.
