Simple input can still create a real challenge
A small control scheme does not make a game shallow. When the input is reduced to a tap, a release, a direct target, or one primary action, the difficulty can move into timing, observation, prediction, memory, and risk management. The player understands what to press quickly, but improving the decision behind that press can take many attempts.
This makes simple-control games useful for short breaks, first-time browser players, smaller devices, and anyone who prefers a clear rule over a long tutorial. Some titles are reflex challenges, while others slow the pace and ask the player to remember a sequence or choose a target carefully.