It doesn't have Canon control ring because this is the exact same lens they already make for the Sony E mount, which does not have Canon control ring.
Right. I guess what I'm wondering is if any third party manufacturer will make a "true" RF lens using the control ring feature? Or will they all be mirrorless versions of the EF lenses adapted for the shorter distance to the sensor? If that's the case, Canon did something unique that will make native glass more appealing to some. I know it's not "needed"; but some will want a control ring.