I would argue that's more your fault for not setting it up. I have a media computer I can access pretty much anywhere to watch or game. Only con being the network speed. I could do the same without the computer by having it on a cloud server but choose not to. And with the method of connecting to said device being done via https it can pretty much be logged into from any device that has a browser.

Most computer towers and laptops I've worked with also allow booting from network.

I could go on but you can already do this if your willing to set it up there's just been no consumer demand for this yet. As I have seen this in corporate networks with thin clients and vms (thou you could launch the connection to the vm via software on a thick tower).

Edit: also Chromebooks and their kin are this to a lesser degree

Point I'm making is fully possible now just why would everyone want this instead of having a personal device?