Not much point in writing a PR if the idea has already been rejected (or is still hotly contested) in the issues. Most of the suggestions aren't just write-some-code solutions, they're design decisions, and if the project owner doesn't agree with that decision? Well, you can fork it like glitch-soc or hometown, or you can use another project that already does what you want (but doesn't have as much traction), or you can keep trying to convince the people running the project to accept your idea. Even quote posts, which they're finally coming around to grudgingly accept as a possible feature, involve a lot of decisions on which posts can be quoted, who gets notified, etc.