That has been my experience on quite a few FOSS projects. I had to learn that the hard way (on other projects, not GNOME). Some are more conservative than others, some may delay making a decision until after they get a patch, etc. Ultimately, since it's your time, you have to do your research before you decide to spend months working on a patch or however much time you plan.
Since GNOME is a large umbrella project then it can vary between sub-projects, I have noticed the ones that are popular and user-facing tend to have a much higher bar for contribution and are much more "cathedral-like" in their design approach, and they kind of have to be if they want to have any kind of semblance of stability. So I don't think it really helps much to blame any project for this or call them "bad eggs", it's their choice of how they want to do things.