I have not seen or experienced that myself or through closer friends. I grew up around boats and running 1 or 2 30amp marine lines with the twist locks and even my own had one and never experienced a failure in the 6 years of ownership (it was bought used.)
On the RV side, I would say about 50% of those I spend the most time with all have the twistlock setup on their trailers in the 30a or 50a flavors and still here I have not heard of any failures on the twist lock. The most common failure I have seen has been the same, the male end of the plug. I considered converting my monaco over to one before I figured out the trick to rangling that 50A cord back into the bay.
