Your computer is more than 7 years old, dude. I mean, come on.
Time is not a good reason for it to be "obsolete" by Apple standards.
What exactly, spec-wise, is limiting a 2009 machine from running Sierra?
And I mean aside from what Apple says?
Is Sierra too graphic-intensive? How far of a jump is it from El Capitan?
I mean, seriously, I want to know where these limitations actually reside.