Maybe participation would be lowered, just not to the extent “they” hoped for. I have personal experience with this - we had some major social media sites blocked, and for a lot of people that was a final push to learn to avoid censorship, even if not in the best way (by sketchy free VPNs). So if you take away something very important, it might turn a person from someone who didn’t go to blocked sites into someone who isn’t bothered by blocking.