Fun fact: if a poor admin can use WP-CLI this will close commenting per every post (and takes loooooong time):
wp post list --format=ids | xargs wp post update --comment_status=closed
And quite soon will come a lot of emails that tells something like ” Reason for failure: A 429 response code was returned from Discourse.” Too fast, too soon and have to wait few seconds — API was in the bad mood I reckon.
But wait, there is more as they say on shopping TV. Every post of WordPress that could close commenting and was connected to Discourse, got a boost and flooded /latest.
So — WP-CLI is a wonderful tool, but in this situation… not so much 