The confusion is that we have different goals.
This method (tape on non-dominate eye) isn't to allow the non-dominant eye to take over unimpeded, nor does it really have anything to do with being cross-eye dominant. Instead, it's intended to help the shooter to shoot both eyes open and get the same eye to consistently be the dominant eye. (Shooting with both eyes open is, to many, desirable in USPSA or self defense applications.) The idea is to strengthen the dominance of which ever eye is already dominant.
Even though I am clearly right eye dominant, my left eye sometimes gets uppity and thinks it's dominant, and does a little battle with my right eye over which one is going to be the one to focus on the front sight. The tape trick seems to help keep the left eye in its place and make the right eye more dominant. I just use it occasionally in practice or dry fire. I've shot a match with the tape once, but I bobbled a mag change due to lack of depth perception.
(I say it's not about cross-eye dominance, since a smart practical pistol shooter that is cross-eye dominant will keep his strong hand the strong hand and just move the pistol over in line with the dominant eye. Not the same for the bullseye shooters, I guess.)
Yay I did it! I shot with both eyes open today for the first time and it was nothing like I expected. I thought that I would have to choose which set of sights to aim with, but my eyes (brain) picked the correct one. I tried it shooting at a "sure" steel target (read up close) so if I missed I would know it was because I was using the wrong set of sights. I didn't do it the entire time because I was out at the range with the Boy on a holiday and wasn't focused (heh heh) on training. We had a great time.