How do you mean? Phone OSes prove the model works, at least for ordinary "productivity apps". Linux kernel features to enforce it exist and are well tested, and are used by Docker and Flatpak. Microsoft implemented the technology, but had trouble getting developers to actually commit to it (which is rational, why choose a harder option if there's no incentive?). And MacOS seems to be doing a good job of balancing increased default restrictions with maintaining escape hatches where needed
There’s a lot of software that doesn’t fit into the phone OS model that people generally find it useful to have available. macOS has tried to bring some of this to the desktop but beyond straight ports of mobile apps their efforts to allow for apps to progressively do more powerful things have largely been failures.
Users are typically not in a good position to make decisions about permissions that are bolted onto a model that didn’t have them to begin with. Think of all the annoying permissions that macOS has currently that you mostly have to click through for a lot of stuff to work (“I want access to your desktop folder”, etc). Software that isn’t designed for a more limited model from the start often does not interact well with efforts to contain it.
