I don't think that is true at all....but I also can't tell if you're arguing for or against that statement, haha.
I guess maybe it depends on how you define "better". But I don't think if you gave Shane an amazingly crafted Szamboti, Balabushka, or similar cue most people would classify as "better" than his Cuetec, that he would actually play any better.
I think the modern quality production cue is plenty good to play truly top level pool. Basic butt, good carbon or wood low deflection shaft, and you're really set for top-level play. Pre LD/Carbon era maybe you'd have a little more of a point but even then I'm not sure that argument holds water.
Now, I'm not talking about a comparison to an absolute POS cue....there is a minimum level a cue needs to meet and then there are personal preferences on top of that. But I think most players of any level can play their best game with something solidly sub-$1k and what I would call a decent cue.