If you were operating in a totally clear, perfect envrionment, yes, I'd agree with you. And if you want to nit-pick and talk about the range of the signal as opposed to the useable range of the link between the TX and the RX, then I'd agree with you.

However, In the real world, radio range isn't determined by weither the RX can pick up any part of the signal, it's determined by the RX's ability to pick up the entire signal error-free (or error free enough to fly, a dropped frame here or there doesn't matter).

So, the question isn't whether an RX can or can't see the signal, it's whether the RX can pick the signal out of the background noise and make enough sense of it to guide the plane.

And that means that in the real world, differnet receivers do, in fact, have different useable ranges given the same TX.

For most quality RX's, the useable range is line of sight, as it should be. But there ARE some inexpensive RX's made specifically for the park flyer market that are just not suitable for applications like RC Combat.