Accommodating a kernel by renaming GNU as GNU/Linux was the major-most mistake by free software movement. Android guys refrained from repeating that mistake as they never bothered to name themselves as Android/Linux.
Just because free software people compromised and agreed to recall GNU as GNU/Linux, there occurred all the confusion that Linux is something greater than kernel almost an operating system although it has never been one and later-on development of Android has decisively proved that. The fact has always been limited up to the extent that there are a few operating systems such as GNU and Android which accommodates Linux kernel in their code.