This is probably the small group who are using 5 string basses with a top load / string thru bridge. It is likely that most people who report no difference are testing on standard 4 string basses.
I do understand the importance of having a good witness point at the bridge saddle.
With a big B string (and only on the B string) and a bent plate bridge, string thru body likely does make a big difference in tone and definition.
I was talking 5's, not 4's.
Ibanez ATK305 is the only one I've personally tested. Not a bent plate, but properly set up, there's no difference on mine. And through-body eliminates the possibility of using a taper-core B.