This is not necessarily the opposite. It is perfectly possible that the knowledgeable people you've worked with actually wanted to pass it on. They just weren't given the time to do it.
You should be angry about overtight deadlines and companies who live by those, not to the actual people. This also points to a possible solution for you: switch companies.
I wish my personal experience was the same, but it has been the polar opposite. In my current and previous roles, there is always too much work, which causes management to pressure development for deliverables, which results in juniors getting pushed aside. It's a terrible cycle and I have no idea how to improve it.