It was not just any anonymous developers, it was Google specifically making Gmail and Youtube not working on the Windows Phone. They refused to port their apps, and when Microsoft created clones (i.e. Microsoft built Youtube apps) Google made them not work on the back-end and threatened to sue MS.

It was just monopoly abusing its walled garden and being anticompetitive, nothing else. Not that Microsoft would behave any differently, if the positions were switched.