There is a flag in your profile called "showdead" that you can turn on to see the comments that have been deleted. There might be some minimum karma requirement for this, I'm not sure.
But I've had it on for a while now and I usually read a few of the dead comments. I see a lot of incivility, inanity, very little in the way of a politely expressed, well-thought out but unpopular opinion.
I didn't claim that incivility does not also exist. And the banned accounts don't show up in showdead anymore, either. What you consider "well-thought out but unpopular opinion" could also be subject to your personal biases.
But I've had it on for a while now and I usually read a few of the dead comments. I see a lot of incivility, inanity, very little in the way of a politely expressed, well-thought out but unpopular opinion.