So what did USSR do? Of course, it interfered, and suppressed the reforms - in 1953, 1968, 1981, and then on much smaller scale in each country separately, as protests broke out literally every 5-10 years.

Not because that would somehow hurt its economy or "road to socialism", but out of the obsession of control, and "teach them a lesson".

Exactly the same thing happened again in Ukraine in 2014...