According to the article this does not seem to be the case:
> Gizmodo was able to replicate the problem. In fact, we were able to circumvent the issue just by changing the name of the Chrome app on a Windows desktop. It seems that Microsoft threw up the roadblock specifically for Chrome, the main competitor to its Edge browser.
> Mozilla’s Firefox has its own one-click default button, which worked just fine throughout the ordeal.
so no, this doesn't appear to be about an app using a backdoor API, it's specifically targeted at Chrome.
Both can be true, though. In this case, Chrome does, in fact, try to work around the standard OS API to register default apps (because it opens a screen where the user is then supposed to actually pick things instead of one-click "it just works"):
> Gizmodo was able to replicate the problem. In fact, we were able to circumvent the issue just by changing the name of the Chrome app on a Windows desktop. It seems that Microsoft threw up the roadblock specifically for Chrome, the main competitor to its Edge browser.
> Mozilla’s Firefox has its own one-click default button, which worked just fine throughout the ordeal.
so no, this doesn't appear to be about an app using a backdoor API, it's specifically targeted at Chrome.