Your worldview (mostly) applies to pedestrian crossings but that's the extent of it.
When there is infrastructure to support all 3 kinds of users, it seems a lot more equitable for everyone to use the space cooperatively.
I absolutely agree one should give way to more vulnerable road users, but that all 3 can have better outcomes (safety, speed of journey, efficiency etc) it all use it cooperatively and conscientiously.
To labour the point, on shared cycle and pedestrian paths with a line down the middle, does a bell ring combined with slowing down to a safe speed not seem like an appropriate warning?
> Why can't the cyclists slow down when they see that there's a human obstacle in front of them?
Because if the space is limited and they actually want to get somewhere, they just don't have time for that? And slowing down often means stopping and causing a traffic jam.
Note that I mostly agree with what you wrote (and I give priority to pedestrians when I'm riding my bike) but there are different situations that have to be taken into account.
Even when you "actually want to get somewhere"?
They for sure have time for that. When I drive my car can't use that as an excuse.