So you are basically saying that Canon is lying about the advantages that come with the RF mount.
I'm saying that the biggest change in RF, the shorter FFD, is of little benefit to telephotos. If you look at Sony lenses, as the focal length gets longer, the lenses end up exactly the same as their longer DSLR lens counterparts + spacer. The other features, like control ring, aperture blade control , and additional communication pins are cool, but these lenses are a big investment, and if someone's going to replace one, they're going to be looking at AF speed, image quality and size/weight, none of which will dramatically change.
Not at all, but does that mean that no improvements are possible? To take your statement to the logical conclusion - is Canon shouldn't be releasing any more improved versions?
Not at all, but that's not what I said. I said that to get a native RF lens, all Canon has to do is build the converter into the EF lens, and that for the current generation supertelephotos, the optical image quality is excellent. Of course, if Canon can make a better optics, they should do so, but this has nothing to do as to whether it's an RF or EF mount.
I don't really know for a fact as there aren't enough RF lens to prove one way or another. Perhaps you can show us how you came to that conclusion.
I came to the conclusion that lenses for mirrorless FF aren't particularly smaller by looking at Sony and Canon's FF mirrorless lens portfolios. As focal lengths get longer, none of the lenses get smaller or lighter in a meaningful way. If you want a long focal length or a wide aperture, it's going to be a big, heavy lens, period. There are no free rides. Basically, if you want a lighter/smaller lens, you need a more efficient optical formula or lighter materials.
Anyways, we'll see in two years from now. If all the RF, FE, Z, and EF lenses of the same class are about the same size, then the size/weight thing will be moot.