The use of them largely depends on your goals as well.
General training/Bodybuilding - probably not necessary
Raw Powerlifter - can potentially throw off grooves if used too much or in place or BB only lifts (as I can attest too) but extremely useful for the reasons TotalStrength suggested
Equipped Powerlifter - Reverse band lifts in some way simulate what a bench shirt, squat suit, deadlift suit does, though, as per raw, still with the potential to throw off groove (though I've yet to come across an equipped log where they train with their comp suits every session so the groove here may be less relevant). Again they help with lockouts etc etc
Athlete - imo this is where they come into their own. As you squat with just the barbell you have the tendency to decelerate slightly at the top of the lift which is the complete opposite of what you would do when you jump for example. adding the bands/chains means you have to continue to drive through the lift otherwise you will get stuck (still not fool proof obviously). Athletes don't have to worry about lift grooves either because they aren't looking to lift more - simply get stronger
Just my 2cents