Partially true, partially a fallacy.
It's like saying, "dollars go a lot further at Motel 6 compared to Grand Floridian!"
It's not exactly that points go further, it's just that the resort is cheaper. For $50, you can get 1 real steak at a steakhouse, or you can get 25 hamburgers at McDonalds. So does $50 go further at McDonalds than at a steakhouse?
Add in the fact that, you can use your points across resorts at 7 months. So if you want your GFV points to "go as far" as BWV points, you can just use them at BWV, subject to 7 month availability.
I think this becomes more of a noticeable difference when you are working a set budget. Say I only have 10K to spend....assuming expiration dates are the same and no other factors...how many points can I get at X Resort vs Y Resort...I'm going with more points for same money.
In my case, I only want 30 points so the difference is minimal...even buying direct at VGF isn't that much more than resale for a small contract.