Yeah, I'm not sure if there's a better solution. Also not sure if those subscriptions are communities or if unsubscribing from feeds will help... I mean you can go two ways here, keep track of the ones you like, reset your account and re-add them. Or go with the mess and unsubscribe over time.
Maybe an idea for future development is to add another onboarding step which details the long list of community recommendations and the user can tick or remove checkboxes before they get added.