I would guess it's for people who need to run automated tests that their Mac M1 software works. Or maybe there's some program that only works on M1 and they need to run it in an automated manner (a compiler?).
Its almost always cheaper to just buy a mac mini than to rent one out 24/7 though. I think Apple also made a tos change banning renting them by the hour as well.
Will take a year for the rent to cover the price of a mini, and it includes bandwidth, IP assignment and power. Not a bad deal at all.
If you're a small operation, maybe. If you're a big company you probably want to have a service, not extra hardware you have to manage, and the rental cost is a rounding error for your software development costs.