The party loosened its grip and began liberalizing because the block was collapsing, not the other way around.

That one is also common on places with violent governments. The people organize themselves, fight for survival and get some victories; the government makes concessions; the people say "too little, too late" and keep fighting for more until they get meaningful change. If you look, the English Revolution also got the most impressive results way after the kind had loosened his rules.