Most of the time, and only if you have show dead enabled, you will see that dead comments are that way for a reason. They are low quality, nonsense bots, etc. Very, very rarely do I see a dead comment that represents some well thought counter argument.
It's also easy to confuse the flag link as a downvote. It absolutely is not that. If a person abuses the flag button too much, the flag button gets taken away from them. I should know, it happened to me years ago. I was quite judicious with the flag button because my default behavior from digg/reddit/youtube was to downvote things I disagreed with, didn't like, or thought was of low value.
So it was taken away for a couple of years. I've since gotten the flag button back and today I only use it for what its supposed to be used for.
Case in point, here are the currently dead comments on this post (asterisks are my own on that last one):
"I know I’m shadowbanned but I hope you see my crap, Dang."
"Jesus H Christ"
"It's called "feet" bcuz it's done mainly with the foots :D"
"Just go to the point and ask him if you can suck his d***"
Not exactly adding to the conversation, if you see my point.