Development for VR is an absolute pain. Until relatively recently there was very little coherence between development frameworks. That made supporting different platforms really difficult, especially when it comes to PCVR vs standalone. The development toolchains have gotten a lot better in the last few years, but there’s still a significant amount of jank that you have to resolve.
This is to say nothing of testing against different headsets and platforms with very different capabilities. It just takes up a lot of development time, which is usually in very very short supply for games companies. Hence, development tends to target the least capable platform (usually the Quest) and let the other platforms use less than their full capabilities.