I might be misunderstanding you, but I don't think any extreme is a good thing simply because being limited to an extreme means having less choice, and that is

I might be misunderstanding you, but I don't think any extreme is a good thing simply because being limited to an extreme means having less choice, and that is a bad thing. There are advantages to centralism, there are advantages to distributed systems and there are advantages to doing the processing locally. The best state of affairs is having all these options available to you when deciding how to architect the best system for your requirements. If a mainframe type solution is the best, do that. If running it on your PC can solve the problem, then do that. If you need a combination then do that. Personally, I think that returning to the "mainframe does it all" concept is a huge step back in terms of freedom, and therefore in terms of potential.