It applies to English too, if you are using anything but US English.
I find it wearing and tedious. I used to love reading US books - with different spelling, idioms, habits, social expectations, and the odd phrase or word I'd never come across. Then revert to British books, read the odd German translation etc. I'd read a Nordic crime novel because it's not set in a quiet English village, Chicago or London, and things are done differently. Apparently that's not permitted by publishers any more, unless you're as lucrative as JK Rowling or T Pratchett.
Many British recent novels, and just about all recent sci-fi are written in American. Not just spelling, but a book set in 1930s London, with a London character who we've just been told lived in the East End all their life, will talk about the sidewalk, the trunk and hood, and such. All judges will use gavels - regardless that in the UK, only an auctioneer uses a gavel, no court possesses one. This sort of thing gets especially silly with things like the Laundry Files - it's parodying Britain, its culture and its systems, yet talking in "Yank".
I've read a few different Nordic crime novels where not only are they written in American, they are culturally appropriated to be set in a virtual USA, called Sweden (or Norway, etc...). Suddenly the Nordic countries have district attourneys, US police hierarchies, US court systems and such. This is particularly grating.
I don't understand why. It ruins far more books than it helps. Above all, I don't believe it would put off US buyers to read of a few places doing things strangely or talking funny.