Power Line's Steven Hayward summarizes a New York Times article (behind paywall) which reveals the inner workings of the Biden White House. It turns out propping up a frail old man who wasn't the sharpest tack in the box when young requires a lot of White House staff time, patience and effort.
The term that comes to mind is "high maintenance." And he is cranky, he yells at subordinates. Because so much behind-the-scenes effort is required for each public appearance, we don't see him often and in his case that's probably a good thing.