If there are regular lines of more than a few minutes to get past the FP+ scanners, and the lines continue all the way to the next scanner, the problem would seem to be that they are issuing too many FP reservations.
Waits that are just outside the scanners, indicate a problem or inefficiency at the scanners themselves.
Both of those things are fixable.
Neither of these has anything to do with the things about FP+ that generate the vast majority of the complaints (limit 3, tiering, no attraction twice, only one park, etc.)