This is not necessarily the case. Although I have no concrete empirical evidence to back up my assertion, I can say that after experimenting with different surfaces over several days, my current mousepad significantly improves my accuracy, both while gaming and doing more menial work inside the OS's GUI. Using the Goliathus, I immediately noticed significantly better vertical tracking than using other surfaces... keep in mind mine is rotated 90 degrees, so that would translate to better horizontal tracking for most people.
That aside, a regular old cloth lined mousepad will serve 99% of people well, but the nice thing about gaming pads is you have options. As to whether the performance justifies the price, that's subjective.
The whole "Gaming mouse pad" thing's a big ripoff. There really isn't much difference between those "Gaming" mouse pads and any old fabric mouse pad they give you for free at a business expo.
I can offer empirical evidence in a way. My mouse pad specifically, is very different from those cloth pads you receive from electronic expos, which typically are smaller than a sheet of paper, feature branding from some company you don't care about but will inadvertently endorse for the remainder of it's use, and feature a bland texture. As I stated in my prior post, I own and use the Razer Goliathus mouse pad, specifically the alpha control version which has a texture and surface not unlike a sports jersey, but more clothy and less nylon-y. The texture is unlike any other pad I've used.
Sure these textures may not offer a performance improvement for your conventional mouse, or even performance mice but it may be that certain types of surfaces are easier to track for different types of sensor equipment. I don't know and don't care to know as this is beyond my desire of understanding. More important to me is the relationship between the mouse and pad texture wise, how it glides, how my hand rubs against it, how easy it is to stop and start moving, whether or not it'll outlast the mouse, etc.
Your statement is not unlike saying "all mechanical keyboards are the same". We know that this is the farthest from the truth. You can't even say "all cherry blue based boards are the same" without getting laughed off these boards, and that's a degree more specific and believable. I would say given today's sensor tech, any mouse pad would do for the sensor, but for the hand, and the feedback, it becomes a very personal affair.