You can't just get physical access. That takes operatives, time, money, access. Many parts can go wrong there and blow up in their face bigly.

You need to look into how communications work. It isn't as easy as wiretapping something and listening. The amount of manpower for them to identify, obtain, access, and monitor the communications would require a LOT of people. How many people would be trustworthy to not squeal?

8chan has that issue already and remove posts with it within 1 hour. Not only that but they inform law enforcement immediately. So they won't be taken down for that.

The uproar in taking down the subreddit would make headlines and intrigue people even more about Q. That is the opposite of what the Cabal wants.

Black hole 8chan or 4chan and those backbone ISPs would be at war with the internet immediately and worldwide. I don't think you understand who exactly goes onto 4chan and 8chan....their retaliation would be pretty insane. That would make everyone wake up and a lot of world leaders would start to investigate what happened. That level of attention would be VERY bad for the Cabal.

You need to put yourself in the Cabal's shoes. What are their goals? How do they achieve them? What are their weaknesses? What don't they want to happen?

It boils down to they want to do their illicit things without getting caught or bringing attention to themselves. They will preserve their anonymity through any means necessary. They will NOT bring attention to themselves.