Not entirely sure how you've interpreted it as if I'm arguing that goalkeepers shouldn't come out for crosses and be vocal, but it's hardly a surprise that you're going for straw mans arguments.
In terms of "helping out" it's hardly quantifiable, it can be coming off your line, being vocal, making a save after a defender has done something daft, it's nondescriptive, mentioning it as a seperate point just further underlines your agenda.
In general, I tend to find it a bit amusing how people pop up once a player is starting to perform badly, and go on about how they've been thinking x,y,z for years. Hey, if you've been thinking something for years but kept your mouth shut about it, then it's probably not the most intelligent argument in the first place. I don't mind a general debate about weaknesses and strengths, and nobody is going to argue that De Gea is the perfect allround goalkeeper that excels in most areas, but his weaknesses can easily be compensated for by having solid cb's. Suddenly redefining what is important is counter productive, the narrative that he's a mediocre goalkeeper that can easily be replaced is bizarre. In the period that he's been here, his strengths have overall made his weaknesses insignificant. Every once in a while there will be feckups, but unless it suddenly becomes the norm it's hardly a concern. Given his overall performances for us, i'm hardly concerned by his form in the run in, no matter the consequences it had on our final league position ( where he certainly wasn't the only culprit )