I would have a slightly different takeaway from this - it's the vocal users, the ones that commented and posted and were active contributors, who were pissed off and left. I would wager a good amount of lurkers who idly browse memes and upvote content have remained.
In the short term, Reddit still ends up with ad impressions, no change, there are a ton of lurkers. But in the long term, this becomes a bit of a death spiral - less new content for the lurkers and they're more likely to be peeled off onto a more active platform with fresher memes, and the remaining contributors have less people to talk to and so they, too, are peeled off elsewhere.
This also means, if Reddit wanted to curate and sell their text data for AI training, that there's suddenly much less of that coming in. Whoops.
Arotrios