I just noticed that the water particules ( and other liquids ) on a surface spill everywhere, in real life, they would be lightly attracted by each other and would not spill all over, just a a small spot because of the attraction of molecules. I know that nobody cares but I just wanted to tell you that and also sorry if I mispelled some things, I'm not perfect in English.
The effect that you are talking about is caused by surface tension which oe-cake actually does simulate but the powder toy doesn't. Correct me if I'm wrong, but in TPT, liquids are more like powders that don't pile up and aren't really liquids.
Also, for lolzy and other oe-cake users, tensile is the only fluid with surface tension which is why it won't work with water. You could combine water and tensile to have a "shiny" liquid with surface tension.