Yes, that's a valid point—mousepads do make a difference, but the difference is more in feel than raw performance. A high-quality mousepad can give you a smoother, more consistent glide and better control, especially if you're playing at low DPI.
However, once you get above a certain level of quality, the differences become apparent. Comfort, texture, and surface type are largely personal preferences—so it's more about what suits your play style than spending extra money on brand recognition.