Even at f/8, is your camera capable of autofocus? Is it at f/11? Perhaps the wall keeping you to bigger apertures is the SLR AF's requirement for f/8 or wider? Perhaps with a MILFF focusing quickly and accurately even at f/11, you could actually get shots you like? Further, technology continues to improve so perhaps the sensors these lenses will be paired with, either starting with the R5/R6, or at some later date, will get better images at f/11 than you're used to at even say f/5.6?
I mean it's not as if there is some kind of chasm of quality between any two ISOs a stop apart. If you're able to shoot f/8 for some shots, and get a usable result, then there will be some shots you can shoot at f/11 and also get a usable result. I challenge you to explain a scenario and image where one would be acceptable and the other dismissed out of hand.
Further the smaller optics will surely sell 10x or more and be used 10x or more than the elephant-leg primes. I happen to have budgeted for a 600/4IS but give the 600/11 to ten guys with equal talent and I'm sure they'll be getting better shots, simply from the shotgun effect, than I will, and the better composition and timing and what have you will overrule any technical demerit of running just a couple stops higher ISO than me.
> If you want to buy F11 600/800mm lens and shoot stationary objects , fine, but there are far better lenses for this type of shot
I can't imagine what they'd be?? Zooms with teleconverters perhaps? Have you gone from being so insistent upon quality that the ISO required for f/11 is simply out of the question, to blithely arguing that some solution jerry-rigged out existing optics is going to be so unquestionably better that you don't even want to see the actual specs for these lenses before locking in your opinion for the world to see? Were you equally sure that the RF 50/1.2 couldn't possibly be so much better than the EF 50/1.2 and therefore no-one should bother with it?
Personally I don't think Canon's gotten where it is by making stupid lenses. They've surely identified buyers for these even if you and I don't know who they are. Mountain climbers? Students? Maybe they're so sharp that they really are useful for professional wildlife and sports? The idea that they wouldn't blur backgrounds artistically is bollocks: even the 600/11 would have the bokeh of a 50/1.0 wide open, and an 800/11 the same as a 85/1.2, 135/2 or 200/2.8 wide open. So not only bokeh city, but the background is far more magnified as well and thus less identifiable.