I recommend shorting it. Reddit today is an absolute ghetto compared to 5 years ago. All of the interesting content and free thinking users have been banned.
I don't think he's talking about a specific subreddit, but rather reddit as a whole. I tend to agree, but I don't see how that hurts advertisers.
IIRC you used to very rarely see actual celebrities in the ama subreddit because it was a weird place where they'd ask you how many toddlers you thought you could fight at once, or maybe someone would get accused of trying to bang a highschooler. Now it's just your standard softball interview space where you go plug a movie, someone asks you what it was like to work with (other famous person), and then you're off to go do the exact same thing on kimmel.
It's advertiser friendly but it's about as exciting as a bowl of oatmeal and as thought provoking as the number eight. The only reason people stick around on reddit is because they're addicted to the skinner box content feed.