Joules...I've been here a long time....please don't troll. You may not know much about lens construction....but some of us have been shooting professionally for a very long time. My first Professional Canon camera body was Pre AF....in fact I still have it. I also have an original ef 50mm f1.8 from the first year of EOS.
Go look up some of my photos....many are to be found on these forum pages.
That's a complete non-sequitur... Taking photos doesn't really teach you anything about building lenses. You've also chosen a basic double-gauss lens as an example, probably the simplest optical formula you will see in any modern lens. The RF 24-70 2.8 has 21 elements (even more than the EF II's 18 and FAR more than the 50 1.8's 6 elements). It's also got IS.
I don't think healthy skepticism is "trolling"... You made a claim that the RF 24-70 should cost no more than the EF version, but without evidence. It does seem to me like the extra IS group makes the lens design (and calibration, if not manufacturing) more complex, but then again I don't own a camera without AF so I don't know anything.