[Afton]

Sure, and if you want to go down the road of constructing metrics for language, you can. I should warn you that you will likely find it fruitless and arbitrary.

Your point about how every variation makes a language is correct. The term is idiolect. Language (like 'English'), is an abstraction over idiolects. But getting people who want to argue about "correct English" to an understanding of idiolects is more work than I can put into a comment during a work day. I'll try and dig up a general description of the issue and link it here.

Edit: http://en.wikipedia.org/wiki/Idiolect#Idiolect_and_language is the best I could do on short notice.