For myself, when I'm in big water, like Grand Canyon, it seems that my pins & clips keep my oars where I want them to be better than oar locks would.
In rocky water, I can ship the oars into the boat by pulling on them. With the stirrup they are pretty much in place, ready to be put back on the pin.
I've seen people on the water and in videos that struggle to get an oar back into the lock, using valuable time in an active rapid. (Check the recent Buzz posts about Hance rapid for one of those videos). Two hands are needed to get an oar back into the oar lock, making both oars not used for however many seconds that takes to get the ejected oar ready again. Those could be very valuable seconds that the boat is not under control.