My stance on Diggins has nothing to do with America or its behaviour in the world, except inasmuch as Diggins' personal presentation and characteristics, and how she is presented by the commentary team and media departments, are shaped by her being American. It's great that you are able to put that aside, but I'm afraid I can't. A constant propaganda offensive that is hell-bent on forcing a narrative of who the audience is supposed to like and dislike is something that I have a history of aggressively rejecting.
I know that with, for different reasons, Sepp Kuss being my current bête noire on the PRR forum as well it may come across like I'm being anti-American, but it's just to do with those two people specifically; hell, last week I was absolutely cheerleading Sophia Laukli, who I really like and is legitimately one of my favourite skiers on the current World Cup. You may not have been here to see the times when it was Peter Sagan, Gabriela Soukalová, Lizzie Deignan or Petter Northug, but they similarly were forced down the audience's throat, and I rejected that narrative likewise.
One thing that did strike me, however, is that in American sports, there is a tendency towards home broadcasts because each market tends to deal with its own franchises, and in Europe that's simply not the case. If you're watching in, say, Nashville, you can expect that if you watch the Titans match, the commentators you see will be biased Titans fans and that's normal. I've had this discussion on the subject of hockey many times. Sure, some of the most biased commentators, like Jack Edwards on the Boston Bruins, will be mocked, but that's just what's expected of sports commentary in most quarters and many fans even say they would be upset if the commentators were replaced by a neutral team, because they like that the commentary team views things from a biased standpoint because it makes them more relatable to the man in the stands.
In Europe, a lot of the time it's simply not like that. Most commentaries on national broadcasters are usually expected to at least maintain an air of neutrality and while their biases regularly show in terms of who they choose to talk about, or the tone in which they talk of certain competitors or teams, the play-by-play guy is at least in theory supposed to call what is happening dispassionately. This happens increasingly less, especially in races where athletes represent the national team, but is at least supposed to be the case, and jingoistic celebration such as you mention with Blomqvist is usually criticised as such.
This is even more so the case when you have de facto international broadcasts which are syndicated to several countries, like how the British Eurosport commentary was used for Eurosport International for years due to English being the lingua franca of most international media. As a result, having a commentary team who are so openly cheering a single athlete or team, screaming "come on!" at them and "yes!" at other athletes' failures, as Patrick and Mike were doing when Andersson failed to best Diggins' time at the Worlds, is seen as flat-out unprofessional.