agreed, especially for experienced musicians. the point here is that if the notehead carries its sharp/flatness in the shape, just like a notehead carries its duration (quarter vs half), it'll become 2nd nature. if a piece is in F# major, then pretty much most of the keys have an implied sharp... A is not A. it's A#. this way a student doesnt have to constantly remember the key sig & what notes are raised or lowered. sort of like python's explicit > implicit.

as far as note being able to determine the key, that'll still be specified as now - this is an additional visual hint.