A revocation list can often be lazily replicated and doesn't require the complexity of distributed synchronization.

If you store sessions then you need to ensure the session has been replicated to every node before you can return it to the user. For revocation lists it is often acceptable that the token is still valid for a short while at some nodes while it is being replicated.

A revocation list is also not considered highly sensitive data, which would be another complexity layer when working with distributed data.