I have used them on occasion. I found the assembly, perhaps easier than common rafter without a ridge. You are only putting one rafter up at a time, it also aligns the rafters to the proper spacing. I sometimes wonder if cutting a simple mortice in a ridge piece is easier than the tongue and fork, I often cringe when I have a bunch of tongue and forks to do, but don't mind so much a line of mortices and short simple tenons. So my guess would be that building with a ridge could perhaps be easier. But then we don't see a majority of them, do we?
If thrust was handled in other ways such as the dropped tie then they found no need to support the ridge. Have an engineer size a true structural ridge and you will find it to be a large timber. This could also be part of the reasoning not to use one. K.I.S.S. kind of thing.
I am hoping others will add to this......
