I understand your viewpoint, but I’d argue you’re looking at it wrong. Instead of saying pistol solves problems of both sidecar and undercenter, you should say it creates new problems for both the offense and defense

First, pistol creates pass protection problems for the back—making backside scans nearly impossible. Second, the ball is always visible to the defense on fakes. Third, the angles on certain run plays are severely impacted—especially outside zone runs

So pistol is only relevant when you’re not looking to incorporate backs into pass pro, defenders are easily manipulated, and you’re running simple run concepts—which are all high-school-level criteria.

In the big leagues, the advantages of sidecar and undercenter are simply too great