Yep, pedestrians do block bike lanes and monopolize shared use paths without regard to cyclists or faster pedestrian traffic, for sure. I take this as a given, that this will happen, and do the dismounting or stopping or slowing, as well as using my voice or bell nicely, that I need to do For example, when pedestrians or joggers are blocking the bike lane when they could be on a sidewalk, I find it effective just to stop in the bike lane. This keeps me out of traffic, and the pedestrians can get themselves up onto the sidewalk. I find stopping around pedestrians to be pretty effective. It only adds a few minutes to my commute or errand.
It's also good to keep in mind that all people don't have full sensory or intellectual abilities. Being a pedestrian doesn't require one to have good vision or good hearing, and there are people with hidden disabilities (developmental disabilities, intellectual disabilities) also. All of these things can add up to unexpected behavior or slow response times of pedestrians. Some dog owners also are quite taken with and silly about their pets (the love-me-love-my-dog gang) to the extent that they endanger their pets without realizing it. I tend to go very slowly around off-leash dogs as I don't want to be chased (which is something that I've had happen as well!)
I hope that a result of the coming (I predict and hope) rapid increase in ebiking, cities will make more separated lanes for bicycles only. I envision a future road infrastructure that looks radically different from the car-clogged streets and pedestrian-clogged shared-use-paths of today. Let's keep working toward that end.
We are allowed to ride on sidewalks in the cities where I live and ride, and I do so when the only other option is a high-speed arterial where I'd have to take a lane. I've found that pedestrians seem to quite understand why I am there, though if it's the lunch rush downtown, it is slow going on the sidewalk.
Happy riding!