Most likely the grandmas living around you had their radiators at maximum.
I have a relative who also doesn't turn on their radiator because otherwise it would be simply suffocating in there.
They've proven particularly useful when due to a mistake in reading the apartment plan the workers installed the radiator meant for the living room in my room.
The further western you go from the epicenter of this shitshow, the more amenities those things get
I don't know if the dials were there during communism as well, but I remember noticing that the radiator in my school did not have one (save for a hex key valve) and thinking it was unusual, so they were already common in the mid 90s.