It seems quite reasonable to presume that the target audience of Mac Pro users wouldn't treat SDD replacement as "routine maintenance" that would be done by the

It seems quite reasonable to presume that the target audience of Mac Pro users wouldn't treat SDD replacement as "routine maintenance" that would be done by the user, but have it done in a service center. And it's completely reasonable to assume that a Mac service center has other macs on hand. Disks on Macs are not really expected to be a user-serviceable part, if some weird techy wants to do that, they can (with some caveats like this one), but the process is designed with service professionals in mind, not DIY end-users.