Human eyesight is imperfect, everyone’s stroke is imperfect no matter how consistent … this is why shots are missed and this thread is devolving into how finely a hair can be split.
The stroke is muscle memory, and it can be very consistent at delivering the cue perfectly.
When an experienced player misses a shot due to stroke error, it's typically the result of trying too hard to consciously control the stroke instead of simply allowing it to work naturally, subconsciously.
But shots can also be missed with a perfectly executed stroke. It's subject to happen anytime there's doubt in the exact aim or alignment for the shot. Most players have a certain type of shot or shots that they just don't see well, as far as knowing exactly where/how to aim. Their stroke isn't the reason for missing these shots... it's how they're aiming the shots.
For newby/inexperienced players, missed shots are a combination of inconsistent stroke delivery and inconsistent aiming skills. Once the stroke becomes consistent enough to pocket long straight in shots with consistency, missing cut shots is likely due to poor aiming skills, like not knowing exactly where to send the cb or not compensating correctly for applied spin.
When the greatest players in the world, with their fine-tuned, machine-like strokes, happen to miss a shot, I don't believe it's always due to stroke errors. Sometimes, like everyone else, they simply don't aim perfectly for every shot, either overcompensating or not compensating enough for speed or spin.