It’s a business relationship at the heart of it. If my business associates can’t provide the service I’ve contracted for, that doesn’t endear me to them, either.
"Keep paying us for the service we aren't giving you or else we'll blacklist you when service resumes."
I don't think you'll get a lot of people signing up for that.
The other risk than losing your spot is paying them and they go out of business anyway. So you're out both the cash and the service.
I don't accept your assertion that it's not practical or realistic. People have been doing it for thousands of years, and will -- and should continue to do so. Just because it's hard, just because it doesn't directly benefit you, doesn't mean it should be abandoned.