I'm not quite sure where the 25% figure comes from, but I would say that I
agree that some people seem to do very well on low-fat/high carb diets.
I've met at least one person who genuinely appears to thrive on that kind
of diet.

Of course there's no reason you can't use a "paleolithic" diet model within
low-fat parameters, IF your parameters are not ridiculous.  A diet of 25-30
grams of fat per day is insane and can't be justified.  But you can easily
eat a happy, well-varied paleolithic diet on something like 20% fat if you
want to.  Maybe even 10%.  You -must- eat some meat and you must eat some
fat to follow this kind of diet but there's no reason you can't put
emphasis on fruits and veggies and less on nuts and meats if you want to.
I would worry a lot about getting enough protein that way, but it could be
worked on.