Don't want to contradict you, but here is how I feel as a drive-by PR-er:

1. Some projects have a list of goal and non-goals. Rejecting a PR because I didn't read the non-goals is perfectly fine and should be encouraged.

2. I agree. But can't this be solved by putting the "burden of PR" on the PR-er? A long checklist of "I have read this" and "I have tested this" should raise the PR bar high enough to make the code review cost worth it.

3. I understand that bad people are a problem on the Internet, but this feels orthogonal to the "no PR policy". Won't those people "do shit" anyway?