It's something I've been banging on about for a few years, I picked it up in a discussion with Dave Maurice and it's actually something that Mark Bell talked about in his recent video blog.
There is a definite relationship between the form breakdown which occurs in the upper back and how well you hold on to the bar. Simply put upper back strength and grip strength are intertwined. I have never met a seasoned weight trainer who had a genuine grip problem; for a grown man who has been training for any decent length of time, let him do an alternate grip and use chalk and it just won't be the grip that goes first . Now you might think that you have had a genuine grip weakness and I'm talking crap, well go ahead and show me a video of your lift and how you failed and I guaran-damn-tee your form will put your upper back in the position where you grip has no choice but to let go.
So I haven't seen much in the way of grip weakness, what I have seen plenty of is upper back weakness. It's not so much to do with guys who start with a rounded upper back on purpose, it's when the form breaks down from the fatigue and causes this hunchback look, lengthening the time to lock out and just generally forcing you into this sort of 'bear hug' type of pose where the bar slips to your fingers and you're left desperately trying to hold on. That's the relationship between upper back and grip.
It's actually a very useful physical *oh shit* switch by your body. If it's something you really can't hold onto and is pulling you down with it, then it's probably a good evolutionary idea if you let that ****er go.
So let me ask you guys a question, what piece of gym equipment forces you to ignore this mechanism and why is that dangerous? Explain to the class, loud voice please.
My solution for perceived *grip weakness* is to strengthen the upper back with Partial Deads, Full Deads, Heavy Rows, Shrugs and anything else which forces your upper/mid back to work. Feel free to use straps!
I've linked Bell's recent video as sort of back up for what I'm saying here.