I’m not sure I share your view of PRs. I still see submitting PRs as something that puts pressure on maintainers. Even incorrect PRs take time to verify and review.
I also don’t see how this differs between the “gap” and the “fence” part of the metaphor. Whether someone submits a rewrite/removal (fence) or a new feature (gap) for PR review, it’s still going to cost me attention.
It's only pressure if you believe the social contract in a PR is that everything that is written is something you're obligated to read / respond to. If you flip that a bit to a PR being the first step in a way of saying "I tried a thing and it worked, what's necessary to make that an actual thing that other can use", then you will sort of land here.
Previously I wrote https://news.ycombinator.com/item?id=48517931
Saying your quoted words is a request for someone to read and respond; it's still pressure and a burden.