It sounded like he was just proposing that people post all content that currently goes in Open Threads in Discussion instead.

I think the barrier to posting a post in Discussion is higher than posting a comment in the Open Threads, and thus less of them will happen. I also think doing Open Threads on a monthly timescale, instead of a weekly one, will lead to less comments in the open thread.

I think a guide on "This is how you post to Discussion! :D" will be more effective at getting people to use Discussion the way ChristianKI wants than reducing the frequency of the Open Thread posts. (That's an example of what I think a method that increases activity looks like.)