This reminds me of how Skype always had limits in the fine print of its unlimited calling plan back in the day when we paid for minutes on cellphones.
Or, y'know, how current cellphone data plans are only unlimited up until the point where you've used enough and then become "deprioritized."
Or how backblaze offers unlimited plans on Windows and Mac but not on Linux because Linux users tend to actually know how much storage they're using.
Companies have a number that is the profitable point for whatever unlimited plan they're offering. They just want to be able to advertise "unlimited" since that's what customers want and they hope people don't go over their "profitable usage" metric.