Earlier quoted context omitted.
And, additionally, if someone is unwilling to fix known issues in PR - then they will definitely not fix bugs in it after it become merged. So for maintainers merging PRs with known issue is basically promising to fix everything not finished.
To the contrary, a developer is MUCH MORE likely to fix bugs in merged code that has users, than in an unmerged PR. It's the users that give motivation to work on the project. Working on a PR is like working on spec. Working on the development branch gives you direct access to the "payment" of users using your code.
- creators are more likely to abandon or ignore projects that have low popularity or are completely unused - creators are more likely to be burned out when there are piles of demands, requests, complaints etc