I think it's always possible to change your bike a fair bit to tailor it to your needs more. I have a 5 inch travel full suspension bike and I changed the forks for 6 inch Pikes, replaced the big chainring with a bashguard and now it's more all mountain and a much more enjoyable ride.
I think fitness is a big thing too. I know folk with big heavy bouncy bikes and they can do uphill and xc on them no prob because they're fit enough.