So in many situations, the crop body forces you to buy more expensive glass to get close (but not quite) to what FF can do. This does not mean that there is no place for crop bodies on the market.
Only when you force absurd rules of "equality" on the comparison as you did in all of your examples. I roll my eyes and laugh when FF fans do this in forums. "Oh, I own a 135 f/2L so you would just HAVE to buy an 85 f/1.2L to be EQUIVALENT to me." No one is trying to be "equivalent" to FF down to the precise mm / subject distance / field depth. No one shoots like that and no one cares. Do FF users buy and adjust their lenses to be "equivalent" to MF shooters? LF? Such silliness is reserved for forum debates, not real life.
A 135 f/2L might be better then an 85 f/1.2L wide open, but it's not better then itself on FF vs. crop. (At least not after a touch more sharpening on crop which is true of all lenses but also a non issue.) "But DoF!!!" Yeah, usually I want a little more DoF, not less. 9/10 I find the shallow DoF on FF to be a frustration and not an advantage. And if you understand bokeh, you understand why there will be little to no difference in background blur in many situations. (Hint: for detail well outside the plane of focus the physical aperture size is the driving factor, not the format or DoF.)
Same thing for comparing one lens at f/8 and one at f/5. No one shoots like that. No one stands in broad daylight and thinks "on FF I would shoot f/8, but I want the EXACT same DoF on crop so I better shoot f/5." It's insulting to even suggest such nonsense.
There are areas where a given combination of lens and IQ is cheaper on crop (i.e. UWA zoom) and areas where it's cheaper on FF (i.e. fast "normal" prime). For most uses crop is cheaper overall with equal performance, though there are areas where FF clearly has an IQ advantage.