Maybe I'm just a cynic but I don't think a celebrity would actually want meaningful interaction with followers, unless it was with minimal extra effort, just to have their fans think that.
I've been surprised for some time that celebrities just default to the major platforms rather than band together and build platforms that work for them - purpose built to engage with fans efficiently, monetise (Patreon-style member posts, subscriptions, sales, paid downloads and so on).
I know Instagram and co have special modes for those with large audiences, but I'm talking about something built from the ground up to serve the creator or celebrity. Sounds like hell to me, but there are loads of fans who would lap it up.