I think I often see this disconnect, with developers on either one side or the other, and usually the distinguishing factor has to do with what their experiences have been. If you've ever maintained, like, anything - not even necessarily open source but even something at work (with users obviously) - for a significant period of time, long enough to see how a project evolves over time, you'd just... understand.
People without that experience can at times be a little too demanding when they don't get exactly what they want the first time. At times the may even act out, often in ways that are actually harmful, like trying to get managers involved to override something, writing negative stuff about you or your project online, or in general getting fairly hysterical and creating a fuss. When you try to help them they get super defensive, often before putting in the effort to understand what it is you even said.
So it's certainly the case that "bug ridden garbage" isn't optimal vernacular, but at the same, what I think can be worse is, as far as communication problems go, nitpicking project maintainer's communication whilst a.) not understanding that their underlying point remains actually true (I.e. "bug ridden garbage"), albeit not beautifully articulated and b.) not giving them the benefit of the doubt in terms of what their intent was.
Now imagine this, but literally all the time, all day, every day, etc... it can wear you down a little thin. Basically, when someone doesn't understand something, which is why the code needs to be reviewed in the first place, some tend to kind of lash out while latching onto something else they do know, e.g. I know that "bug ridden garbage" isn't a graceful way to talk, so I'll attack that.
Anyway, I'm probably not explaining this very well, and I think it's just something that people need to experience themselves. I've come to take people who are rough more as a compliment than anything, thinking, "this person thinks highly enough about me that they can just say what they really think, so I better not disappoint them by taking that trust and trashing it", obviously there are limitations, but this has helped me so much to learn from people smarter and more experienced than myself.
I'll just say one last thing. From what I've seen, the people who do tend to get defensive and kind of nitpicky about maintainer communication tend to not succeed when they become project leads themselves, and they usually just change jobs. O and obviously the maintainers who have the ability/experience and are blessed with grace, diplomacy, communication skills or however you want to call it, obviously tend to enjoy the most success.