I suspect a lot of open-source folk would not appreciate this, but in my experience as a maintainer of a small-ish project, the overwhelming majority of contributions are well-intentioned but not very helpful (of course, the few contributions that are extremely helpful more than make the whole process worth it!).
It creates a fairly awkward situation where the maintainer doesn't want to be rude and reject the contributor's work (which they have spent their own time making and are sharing for free), so they reluctantly take time away from solving real issues and validate the patch instead.
I could see how erecting deliberate roadblocks could avoid a lot of this discomfort.