Why are these twits so intent on mixing cyclists with pedestrians?!
Because if done well it works.
The three cycle paths I use the most, one is wide and mixed pedestrians and cyclists. There is a subtle (slightly lighter) "line" down the middle which means people are pretty good at moving onto one "half" of the path when asked. Works really well as long as you have a bell on your bike.
The two others have two narrower, separate paths for cyclists and pedestrians. All that happens is that pedestrians just walk on both paths, I assume because the cycle path is slightly wider. This includes especially for some reason dog walkers, resulting in much slower progress.
Put the path along/adjacent to the road and it either becomes an excuse for close passes or a car park.
Quite possibly the reason why none of them work is because they are all used so inconsistently and signed even more consistently no-one really has a bloody clue what is going on.