Wait ... I've only just read this ..... you mean that XBox players have a "family share" that gives them multiple accounts, even though they don't buy multiple accounts with Frontier ???
Yes, thats an advantage of the XBox now. We only buy gold once, then share it to all other accounts on the Xbox. All games are bought for the XBox as a whole. Thats the idea of a console. Buy the game once, and anyone who has an account on your XBox can then play it. The best thing is, that because a basic MS account is free, you only need an email address to create one. I myself have two profiles with Microsoft, with entirely different Gamertags.
Incidentally, the same thing also applies to the PS4.