Just the cursory information in the article suggests a deeply flawed protocol for their study.
You would get similar results asking women if they were orgasmic.
I have... it would astonish most folks to realize how many women, particularly women over 40, rarely or never have orgasms.
This is not due to a lack of a clitoris, it is due to a lack of persistent and detail oriented sexual partner.
Given the huge variety of skill and even interest in any given partner, self reportage is the weakest possible form of data... little better than anecdotal.
The G spot is even harder to find and harder to get at and harder to stimulate. But I have found that all women I have been with have a particular area in the anterior vaginal wall that is more sensitive to stimulation that the surrounding area.
And I have found a difference in how women react to stimulation of that area ranging from the sensation that they would pee themselves ( many of whom did, a little, upon climax) to women who found it annoying, to women who found it deeply pleasurable, but not necessarily leading to climax.
The thing is, that it is definitely in a specific area ( within normal human anatomical variation) and has a markedly different reaction to stimulation than other internal areas.
Given that this area needs no MORE nerve endings than any other area in order to be connected to a specifically pleasurable center of the brain... and given that the actual nerves engaged in G-spot stimulation may not actually even be in the vaginal wall, but might be the the bladder or other tissues adjacent, the study cited seems far from meaningful, much less conclusive.
You would need to have women have sex with proven performers- or even better, with a series of devices designed specifically to stimulate the G-spot in order to determine if there was any consistent response across a population.
On its face the cited study is idiotically flawed.