Hmmm. I don't think the higher poundage masks anything. Sure, it pulls the string off the fingers faster, but make a bad release, and it won't fix it. There is some truth to the observations that lighter weight bows are more difficult for some to hold on target. When I shoot a light bow, I hold too long and have difficulty getting off the string, which ruins my accuracy. Yeah, it's a head thing, but it is what it is. On the other hand, shooting at one's maximum poundage can also cause other form problems, like collapsing, severe plucking in a subconscious effort to dump the string, etc.
Shooting a heavy for me bow requires my complete attention and focus. I'm much more conscious of engaging my back muscles and getting proper alignment and a tight anchor. Because of that, I usually shoot good (for a while). But, I no longer have the stamina I once had and tire fairly quickly. After 25-30 arrows or so with a heavy bow, my accuracy goes down pretty quickly.