No abstraction is perfect. Every abstraction, when encountered by a user, requires them to ask "what does this do?", because they don't have the implementation in front of their eyes
This may be an easy question to answer- maybe it maps very obviously to a pattern or domain concept they already know, or maybe they've seen this exact abstraction before and just have to recall it
It may be slightly harder- a new but well-documented concept, or a concept that's intuitive but complex, or a concept that's simple but poorly-named
Or it may be very hard- a badly-designed abstraction, or one that's impossible to understand without understanding the entire system
But the simplest, most elegant, most intuitive abstraction in the world has nonzero cognitive cost. We abstract despite the cost, when that cost is smaller than the cost of not abstracting.