Comment by cvrajeesh

my 1$ hypothesis - partner company to which Onedrive UI project outsourced didn't had any Linux machine and all developers/QA working for this partner company were Windows users, to improve compatibility matrix they had kept few Mac machines in the office to run tests. Moreover this team might not received proper spec about the backend API at the initial stages of the project development, would have receive only at last stage of the development. So they try to get it working only in one or two platforms to make the release happen :)