I know what you're talking about and it's not the same thing. When you are going for reps, you have to breathe. When you are going for max effort, you can hold the breath in this position to use it to your advantage. I wouldn't want to "leak" breath and then get just shy of locking it out, and have my core too deflated for the extra demand. I know some very experienced lifters that can exhale really hard at their sticking point with great success in blowing through it, but again, not the same as the typical "in on concentric out on eccentric" rep breathing.