The steps of aiming/shooting:
1. While standing up, select a shotline
2. Getting your cue and body on that shotline
3. Keeping everything on that line until the shot is completed
Most videos and posts about aiming focus on the first step and that is often defined as "aiming" in pool. That is all well and good, but usually for an experienced player, that is not a problem at all. The aiming is usually crystal clear from up above, but gets more difficult in step two. In step two you have to get down on the line you saw and trust it. If you rely on imaginary lines/balls then you also have to reproduce them accurately. That is usually much harder, because not only are there moving parts, but the perspective is much different, so it's hard to trust what you saw previously.
To the credit of manual pivot aiming system, they adress this problem. They give you a detailed list of instructions on how, at the very least, to get your cue on the shooting line in the shooting position. Ghost ball and other such traditional aiming systems usually give only vague instructions, that are supposed to be customized to the shooter. If this is poorly done, then a shooter may actually benefit from pivot aiming.
Sadly, pivot aiming kind of suck at step 3, especially systems where the cue pivots in both directions, depending on the shot. It's really hard to get good, consistent body alignment when the movement is different every time. There are one direction pivot systems, but even they need some variation in amount of pivot usually, so they also are problematic. If you observe people demonstrating manual pivot systems they often jerk their strokes. They realize that they're on the right line and try to pull the trigger before they drift off it. It's not a good way to play, honestly.
I find it a useful diagnostic to shoot the stroke with my eyes closed (and a camera recording). It is also very enlightening to watch others do that. It seems a large part of the problem for many shooters is keeping unintended spin off the cueball. The worst players can hardly hit the cue ball with their eyes closed. To me it shows that step 2 and especially 3 are the hardest part of pool, and deserving of more attention than step 1. If you need your eyes open to strike the cueball halfway decently, then step 2 and especially 3 have been failed in spectacular fashion. It's very rare to see a cueball, perfectly struck without sidespin, missing the target in this test unless it's a very high difficulty shot (razor cut from a distance). To me that shows that usually it's not selecting the line while standing up that is the problem.