I'm thinking a third reason played a big part too. Weng has shown a pretty terrible attitude towards her teammates this season. Refusing to take handshakes, not congratulating good races and whatnot. I mean cross country is an individual sport but I wouldn't say team spirit doesn't account for anything at all when it comes to the relay. Weng definitely comes up short in that department, judging from the outside.
Well, there is some correct in this and some "wrong". Weng is an incredible competitive person, and when things go south she needs some time after races to just get things out in a way. The other teammates know this, they have been on her team long enough to know it, and they joke about it. Northug is the same, and it can rub people the wrong way sometimes, but most of the time they know it's one of his quirks and they for the most part accept it.
Weng praise her teammates a lot in Norwegian media, and even at Tour De Ski she finished and stood there yelling support to the others. So it's a bit true sometimes and most times not. It's more of her being in that bubble from a certain time to a certain time and then it's okay. It's a team you know, they all know that each person have their quirks, and that's Weng's.
She's by far the most emotional person in interviews after races, both good and bad.