Being nice is not overrated.
Anyone who wants their advice taken seriously would be well advised to present themselves as the kind of person someone would respect and want to take advice from.
When a rude, hostile person is presenting me with relationship advice, I am far less likely to pay any attention to it than to advice given with grace and empathy. That is because I assume that someone that angry and hostile probably is making a mess of their own relationships, so why would I listen to them at all? I might also assume that they are mentally ill, depends on how bad it is. I definitely think that about one person who posts very frequently here, and I've only been here a few days.
So, if others are like me, and I suspect many are, you nasty peeps are wasting your time, and your keystrokes here.