Fair. I think a better way of putting it is that they lacked the unity to agree to just keep firing on people until they won. A relatively liberal culture is one reason government forces won't do that; in the case of someone like Ceausescu it was more that the generals tended to think his last few years had been a disaster and the rebels had a point.

Every communist regime that collapsed was in the process of liberalizing, except Romania, which wasn’t overthrown peacefully.

China didn’t collapse in 1989 because they were the only communist regime able and willing to massacre protestors.

"relatively" can cover a lot of ground :-)

From my naive observation, the regimes of Eastern Europe had lost their will to perpetuate. (Everybody saw, including party apparatchiks, that the people in the west have better lives. Or at least better goods. :-) )

The cynical take would be that the (smarter) communists in power prepared themselves for the transition, positioning themselves to benefit after the change.