Back in the day when i was racing motocross we were using split links ,because you were often removing said chain to clean it ,and back then it was de-rigure to boil the chain in a tin of wax/grease after a shitty meeting .
I used to see split links used in some safety critical areas in industrial applications (chemical industry). Mostly with lock wire, but not always. Not on any high speed applications I can remember, but some taking serious load. It’s the side plates that take the load in the end. I think the danger of split links is the possibility for damage/ stress on cycled use. The danger of riveted ones is user error on application. Choose your poison…….
I have a rigid frame BSA which doesn't have removable wheel spindle and the only way to get the rear wheel out is by splitting the chain. So it has a split link but as it only makes around 20 bhp it doesn't worry me. An old bike I had years ago came with a clever mod to the split link that a previous owner had done. There was small strip of very thin tinplate beneath the split link which was folded over the split link to prevent the legs separating. I doubt if that could be done with most modern chains as the clearances are much closer.
