If you’re fine being a team playing in the ECL then yeah, missed sitters don’t matter. But in order for us to get in the top 4 this season and play CL football, every goal and point matters.
If Son or Kane or Dele buries one of those missed sitters we get 3 points. Those missed sitters and 2 points may come back to haunt us later.
Then if we are sitting just outside the top four towards the end of the season we’re going to inevitably blame the usual Dier, Sanchez, Lucas, Ndombele, etc instead of remembering who missed those sitters.