Without actually simulating networking, this feature is useless for anything more sophisticated than a single room with a mirror. The most difficult things in VRC world dev involve networking and to not include it in the simulation tool for so long is a deterrent to the adoption of new systems such as PlayerObjects and persistence, because there is no fast way to check assumptions about how they work (documentation is not enough). Unit tests for systems such as custom forks of OWML or SaccFlight can take a while to build even with all the content stripped-out, which makes any testing extremely time consuming because it requires a full build and upload (The local client also doesn't reliably test networking either, but that's a different issue).