Think of it this way: you now have the opportunity to discuss pricing with all the backup vendors in the knowledge of what Microsoft 365 backkup will cost. The other vendors might or might not reduce their proces to win business, and if you choose one that uses Microsoft’s backup APIs, you might get the speed advantage that Microsoft has (because the data is all in its datacenters) with a nicer GUI and better features.

As I see it, this offering, since it’s priced by the GB rather than per user, is only competitive for exceedingly small companies and tenants. Perhaps that’s the point, as I’m sure Microsoft is taking pains (for now at least) not to cannibalize sales from partners such as Veeam, et al.