Here's the things bone presses. Most people can't tell exactly what 6 inches looks like visually vs. say 5.5 or whatever. So when a woman says that she only cares about the amount that is visible, she is surely right (though during sex more than the visible amount plays a role often a very significant one.) but what she thinks of when someone talks about a 6 inch cock may instead be a 5.5 inch visible cock which is 6 at bone press. People rely on the standard way of measuring penises to attach numeric meaning to what they see. So you can't so quickly say the bone presses are bs; you don't know whether the visible cock length that you associate with a certain number really matches up to that number BECAUSE bone press measurements are so pervasive.
Besides, if a guy has a lot of pubic hair, would you suggest he subtract that amount from the length of his cock (perhaps women who prefer the shaved boys would say yes to this just as a motivator to get the guys to shave... but whatev
The other thing is that we all know that a guy with a 9 inch cock who covers 5 inches of it in fat isn't as good as a 9 incher without the fat. But what's wrong with just saying that he has a 9 inch cock with only 5 visible inches and recognizing that his 9 incher isn't as useful? Why conflate the idea of visible cock with your cock itself. That would imply that for some, exercise is ACTUALLY A FORM OF PENIS ENLARGEMENT which seems very fucking strange.
Furthermore, this would imply that more men than we think have penises with absolutely no dimensions at all. If size is only visible size, then guys who completely cover there cocks in fat have penises that have, literally, no size. A really fat guy who would otherwise have maybe 4 inches would have to say that his penis had no size at all... would he even have a penis if it had no dimensions? Just pointing out the weirdness of this way of looking at dick...
Also, guys don't have as much fat down their as women usually, so bone presses aren't as misleading as they would be if women had dicks and used them