> History also shows that creates instability

I would say Russia, China, and North Korea (all well-known to disappear people) have been incredibly stable. Even countries that were quite liberal (e.g., Iran, Myanmar) have worn their populations down into compliance in their major cities. Even the liberal West is borrowing from the same playbook (e.g., police raids on investigative journalists, politically motivated prosecutions).

The strategy works, but as you imply, maybe there's a breaking point... or maybe totalitarian states have figured out how to get as close to that line as possible without crossing it.