Therefore the argument 'How come X is a language while Y is not' doesn't make sense if X has their own country and Y does not.
It's easy to imagine Norwegian and Swedish being considered the same language if they were the same country. It'd be a language with multiple written forms, but Norwegian already has two of those anyway.
But you can only get so far by simplifying the issue to say that language borders are national borders. That erases a lot of the linguistic complexity of Europe, it defies reality in Africa and South Asia, and it just wouldn't make sense at all in North America. (What's the Canadian language, besides a joke on South Park?)
Ie same way that people in Luxemburg want to point out that they have their own language different from German, rulers of Morocco (who are Arabs - majority of Morocco's population native language is Berber) want to stress that they share same language & culture with rest of the Arab world.
In other words - if you are a country, you have the option to have your own language (even if it's mutually intelligible with a major other language). If you are just a part of a country, that option seems off the table (ie you need a non-mutually intelligible language to make that claim).
[1] http://matadornetwork.com/abroad/why-hindi-urdu-is-one-langu...