It doesn't have to be an account ban. I've recently started playing games on my old Nintendo 3DS again and discovered that I've lost my Nintendo Network ID password and closed the associated email account. That leaves me in a state where I can't log out of the account on the console without losing the associated digital software licenses.

Not that that's Nintendo's fault but I think something like this will be the fate of every account that's not used, closed or deleted for a long time and owning your data and software possessions would protect against it.