They do not own the printers. People do. I for example would never sell stuff like this. Way too much work, you need all the packing materials, your prices would be 100% controlled by an external entity. Maybe some people would do it, but how many? How reliable would this be?
Which perfectly works with my previous point. You as the designer would have limited influence on the print. Sure, you can give the print profiles, etc. but we are already at a point where we have 3 completely different machines, with different requirements. You could not guarantee, that P1 and A1 owners use the correct plate, you might have drafts that cause the part to warp while printing, you do not know the wear of the printer.
Heck, in the end, people could even just get the QR codes from the BBL filament and use the cheapest one to maximize the profits.
You have no influence over the QC, which is a big red flag for a manufacturer.
How much money do you think you can make? Lets assume you are right, a lot of people switch. Now you are competing against a global network. The prices will drop massively. In the end you might make a few USD / Euro per part you sell. Is that really worth the time to set up the print, your wear and tear on the machine, the trip to the postal office to ship?
You would have to store all possible extra filament, that an order might require. You might have to get additional AMS, you would have to have all the spare parts, in case something might happen to your machine. It is more work than you might imagine.
Well crypto isnt doing to well at the moment. If it will ever reach broad market acceptance is yet to be seen, and at least I think, quite unlikely. Digital currencies, like the electronic Euro, have much better chances as they are state backed. Sure it is a disadvantage for the true Crypto supporters, but 99,9% do not care.
This is just for small plastic parts. You are missing 90% of the other components for most products. Yes, some people might like building their own stuff, but, once again, 99,9% do not want to do it.
Summary
I do not see the potential. You would have a ton of small companies trying to sell their machine time, while even having to share some of the potential profit with the market site. They will not have the scale like larger print farms, you have now all over the world. If you want it cheap, you go to China. JLCPCB for example offers it at damn good rates. If you want it fast, you go to a local shop.
They all run dozens of machines. They have the economy of scale, much lower overhead, no third party to share profits with.
I think it can work, for a selected market segment, but it will not be as big as you think. Neither the owners of the machines, nor BBL will make that much money.