All true but such difficulty can prevent the instrumentalist
from engaging with another kind of difficulty. So ok it's easy for a pianist to make a note but because it's so easy they're expected to do tons of them, often in counterpoint.
I think guitar's brilliant because we're somewhere between the keyboard (maximimum availabillity of notes) and the violin (maximum abillity to express notes) so not only can we play chordal accompaniments we can also make expressive lead melodies.