If I'm being charitable on both of your points, it is, in fact, rather hard to keep track of where you learned stuff, especially in a field where you run into the same or similar claims from different folks, or you've had a hunch based on connecting the dots from different folks and now that's just part of your mental model of how things are. I think a lot of folks get confronted with that when they try to write, and instead of doing the leg work to track down something to back them up, they just make it mushy.

Academics are supposed to be trained in the hard skill of remembering where you learned stuff and referring to it appropriately, but it seems that they can be just as bad, or worse at just slapping some citations on something to make it look credible, even when the citations in no way back up what they're actually saying. (There's a lot more where that link came from over at The Last Psychiatrist, if you want to become deeply depressed about the state of medical "science").