Must be affected by screen resolution: I tried a machine with small display and low res > no width scaling available
On other PC just now installed 10532, same resolution, still no hor resize, but width now less than half my screen. Same monitor.
Maybe the two posters above can say what that Res was, and this way maybe we get an idea of what the Res is that won't allow a change, so in the future people with this question will have an answer.
perhaps a threshold, Idk. Didn't find an article yet at MS sites upon the issue. Arseny is the one who knows these things but haven't seen him since quite some days