I've noticed that in some old competitions there were many athletes who did not drop the bar, but instead lowered it.
You may see them in this video.
Why has this habit changed? Nowadays, all the people I talk with assume that you must absolutely drop the bar in clean and snatch. And on the web, I have found just one guide about how to lower the bar in those exercises.
Ps: my interest in lowering the bar is because I don't have bumpers and with my cast iron plates I'd damage my floor if I drop them. But also because I'd like to learn also the eccentric phase of clean and snatch. Just for curiosity.