I know that there are normal launching methods, but the one with stacked entitys produce allot of lag, and not everyone is willing to build one some tall mountain just to be able to fly off.
plus yk, making easy launchers is one possible use, but they also would make good parkours/minigames on their own (take a bunch of free floating slime bocks with different preasure plates and who is the first up top wins, or one incorporates them into a normal parkour)