Neither am I happy when a musician belts out "Everybody, JOIN IN THE CHORUS, come on you can sing louder!" - Pal, I paid good money to sit right here and watch YOU sing.
Getting the audience to join in is a skill, and it doesn't consist of yelling at them. Doing it right can range from gesturing to indicate that singing along would be welcome, to Pete Seeger's style of encouragement and teaching the lyrics. But if the musician is good at it, s/he isn't yelling at you, because s/he doesn't have to, and because s/he realizes that not everyone wants to sing.
Done right, it also doesn't feel like the musician is being lazy: it was clearly more work for Pete to teach the audience a chorus or two than it would have been for him to just sing it. But equally clearly, he liked that work just as he liked the work of singing and playing an instrument. (I went to a concert by a different folk musician a few years ago, and I liked it, but it was also clear that this guy had wanted to be Pete Seeger when he grew up, and wasn't, and not just because Pete Seeger was still being Pete Seeger.)