Anything that requires server-side storage is a good reason to ask for an account, IMO. Theoretically you could assign a pseudo-account and store the id in client storage to have a shareable profile, but then you'll have to figure out how long you'll retain idle pseudo-accounts. (Assuming that completion detail is in client storage, at least for anonymous players).

A consequence of me being a freeloader too is that you don't have to change your plans to please me :-)