Earlier quoted context omitted.
Apparently here: https://news.ycombinator.com/item?id=15725493 Certainly not a productive comment. A quick scan of that users's history seems to indicate fairly reasonable stuff: https://news.ycombinator.com/threads?id=xiphias&next=1582220... (among others) Given a lot of other reasonable posts, (apparently) one low value comment seems to be able to get a user shadowbanned. That strikes me as a bit excessive.
I see this from time to time and it frustrates me. I would love it if people above a karma threshold could vouch for shadowbanned users with a recent history of more constructive comments.
I have vouched for perhaps hundreds of shadowbanned comments, is that what you mean? Or vouching for a user directly?