You'd be surprised how easy it is to ban specific protocols or apps, if you put your mind to it. DPI is dead easy this days. Again, Russian example is right there, the only thing that managed to resist the block so far was Telegram, because they're doing some very advanced block avoidance. Russia is poor, and losing brains very quickly, a country with better equipment and people will not have this problem.
Yeah, it's resource intensive, but that's ISP's job, and they have equipment and motivation already. Small ISPs if they still exist will die, but that's just added bonus. And you don't even need the complete blockage, you need to make it annoying enough to use so it's not very popular, so most of the communication will happen on platforms that are under control. You can't fight all the nerds, and you don't need to.
It's not a leap, it's the only next logical step. A government doesn't start carding everyone on the internet because they're bored. They do it because they don't want uncontrolled communication for some reason or another. "For the children", of course, why else. That's why everyone needs to have an ID app on their phone, and all the websites should be tied to it. It's for the children.