Exclusives are what makes people flock to a certain brand. For example if you love the Halo franchise, then we guess it makes sense for you to keep purchasing the Xbox platform. Now Google for the most part has been pretty generous with its products and services and have typically made them available across the board, but no more.
At least as far as Chrome apps are concerned, Google has recently announced that they will be ending support for Chrome apps that aren’t run on their Chrome OS platform. This means that soon Windows, Mac, and Linux users won’t be able to use Chrome apps anymore. This won’t happen immediately but Google will be phasing them out slowly.
By the second half of 2017, the Chrome Web Store will no longer display Chrome apps for those operating systems, and by early 2018, users won’t be able to load Chrome apps anymore. Note that this only affects apps, so extensions and themes will still continue working as they should and will actually be given more focus on the Chrome Web Store.
As to why they are doing this, Google says, “For a while there were certain experiences the web couldn’t provide, such as working offline, sending notifications, and connecting to hardware. We launched Chrome apps three years ago to bridge this gap.” However these days they are no longer necessary or needed as much, hence the ending of their support for Windows, Mac, and Linux.