A quick bit of research tells me that escalators have been around for about 120 years, so not an entirely new phenomenon then you would think.
So how much intelligence is required to figure out that there might be someone behind you, and it's really not a good idea to dump your worldly belongings on the floor at the end of the escalator and regroup, causing those behind you to hop, skip and triple jump their way to safety?
I narrowly avoided getting my foot hooked in the handle of a bag of laundry and flying face down on the floor whilst noticing that the woman responsible for this was looking surprised that so many others were darting about trying to avoid her.