Decentralized operating system on a network

I am pretty new to operating systems and networking so a lot of this may feel impossible or maybe something like this already exists.

I was thinking if it was possible to make an operating system decentralized over a network. What i mean is that a network act as a operating system which could pool all the resources of the connected machines and a user could login from any machine and access his files or run a heavy process on multiple machines. I mean sure there are limitations of the Ethernet cables, routers, etc but still some heavy processes could be distributed easily and could help to pool resources of all devices. This would be great in offices, colleges, etc where there are many machines but of low configuration.

I don't know if something like this already exists if it does than please let me know.