IMHO as a random user is that, given the nature of the fediverse, that makes more sense to be an option for instance admins. I'm personally more inclined to leave that decision to each user, but I see how the network effects play a role and how someone would want to enforce their decission on their own instances.
Anyway, it's an interesting discussion and I like to try to understand the consquences of each implementation.
Thanks for the warning! I'm doing a backup of the subscriptions and will check in a few days.