My key objection is that it doesn't offer any additional value: if you are the sort of customer who would do this, you are also the sort of customer who would implement the same chain of commands to backup to a virtual machine that you owned, eliminating the attractiveness of baxx.dev as a aggregated target. What additional value can you add?
If you can do it at a price competitive to what I can buy storage (and everything that comes along with housing it) and worry about it then it's one of the few things I'm happy enough to have a managed service for.
edit for a bit more context: I do a lot of video work so my storage needs are constantly growing.