I think the better question is do you even read what you write? You're the one asking who defines what is country and complaining about putting labels on things. Your point was all music is an expression of art and putting labels on things just creates limits. I'm simply pointing out that Eminem sings hip hop and rap, Patsy Cline sang country and Michael Jackson sang pop. That's what their music was. The only "limits" were the ones they put on themselves by not expanding to other genres. I gave two examples with Kenny Rogers and The Wreckers singing in different genres and there are countless other examples I could use, but since so many on here love Hank III for whatever reason, let's use him.
Hank III played bass for a heavy metal band fronted by the lead singer of Pantera. He's part of two punk/ psychobilly (whatever the world that is) bands named Assjack and Arson Anthem. He also supposedly sings neotraditional country, but I think his idea of country is flat out awful. Point is, he's not set by limits, he plays whatever he feels like playing, but that doesn't mean everything (if anything) he plays is country music, just because he's Hank Williams III and has more country royalty in his bloodline than any other living person with a name not Carter.
Music has no boundaries, that is proven by how far music has come throughout time. But it's simple and necessary to categorize music that way when I want to hear some country music, I can tune and find George Strait, Alan Jackson, Jamey Johnson, etc. I won't tune in and find Michael Jackson or Eminem or the Beatles. When I tune into a hip hop station, I'm not going to find Alabama or Johnny Cash, instead I'll hear Lil' Wayne, Eminem, 50 Cent and the like. See how that works now?