Yup, but if you cover the right spaces, you remove most of the threat for that specific area. It's why the near post man cuts out 50% of corners, but is never marking anyone.
It's just the pro's and cons of zonal or man marking, or a mix which is what we seem to do, and what most teams do.
Man marking isn't always easy though, as defenders are second-guessing, and the attacker knows what's coming and gets the run at the ball, to attack it, which is easier.
Was just a good set piece, which had the stars align, roll that again another 10 times, and 9/10 the cross doesn't hit that area with accuracy, the striker gets blocked, it doesn't hit the target, or our defender blocks the guy going after Steffen.