Timed suspensions are initiated by humans. Most are initiated by moderators (either elected by the community or appointed by community managers) and are limited to 1 year. But employees have the option of suspending users for longer periods of time. These are exceptionally exceptional.
If we suspend an account for more than a year, there's a good chance we'll want to suspend on every site on the network. Instead of actually logging into each site separately, there's an automated process that suspends in the name of the Community user. In addition, accounts are unsuspended by an automated process once the time has elapsed.
People have come back from year-long suspensions to be productive members of the community. We don't expect people to return from 10-year-long suspensions. In fact, many accounts with long suspensions were actually duplicate accounts set up to cause problems or people who are no longer interested in participating in the community. It's the very definition of human exception handling.