This is so, so important. I'm not quite as good at this stuff as you or T3hPwnisher. I don't compete and I treat strength more like a hobby, clocking in way lower on the discipline scale than either of you guys. Even still, the same principles apply to us all.
For me, the casual but consistent lifter, it is not a matter of believing I can get better, its a matter of knowing I can, and believing that doing these things better could quite possibly yield a 700 pound pull as a lifetime natty. Maybe it won't but I'm definitely not ruling it out before I give it a shot.
I guess I don't see any real value in declaring something out-of-reach when it might not be. Not if it is something you're interested in reaching for, anyway.
Great discussion here.