I think what they're trying to say is some subreddits auto-collapse comments from users with low karma and recent date of creation to combat bots. If reddit gives any more weight to high karma users I can tell you as one that it definitely doesn't seem noticeable at all. Right time and right place comments are always the ones that end up on top.

On most big subs if you have a fresh account your posts are hidden by default. Maybe they have to be manually approved? Not sure.

Source: Don't have a persistent reddit account, just made a new one for the few times I wanted to post something.