To add to this, you can also be automatically shadowbanned by spam filters which, at times, can be quite aggressive. I was once shadowbanned for "getting caught up with a spammy IP address" according to a mod.
That happened to some guy and he kept using reddit as normal for three years until he found out. Took it pretty well. His history is painful to look at. Just talking to himself, nobody ever responds or upvotes him.
Was in /r/TIFU recently, too lazy to get the link.
I saw that too. That's what made me check if I was shadowbanned. I'm not nearly as active as he was, but it made me realize I wasn't always just late to the discussion or something.
