Done charitably, I think the mainframe model of shared compute does meet most person's needs where they don't need to care about latency. It would allow us to take advantage of economies of scale. The problem, imo, is that no one has an incentive to do this as a service, so it would turn into rent-seeking.
But I do care about latency . . . and I want things to still work when the wifi is dodgy. I already find things like Office 360 deeply frustrating (only use it for work).
Sure, a shared model does make sense in many ways. We could share within a family, neighbour cooperatives, and similar scales. With the users co-owning the means of processing.
But the current model is that we all rent from organisations that use their position of power to restrict and dictate what we can do with those machines.