[superjambo]

could be ISPs trying to improve user security generally to prevent lots of their customers becoming DDOS zombies resulting in more contention & customer complaints.

[arkades]

Not a bad rationale, even if consumers don’t complain. DDOS sucks up a lot of bandwidth in aggregate, and this is a cheap way to reclaim some of it.

[gspetr]

That's highly unlikely as we've recently learned from "Internet Chemotherapy": https://news.ycombinator.com/item?id=15946095

ISPs are unfortunately the problem, not the solution.