The thing is, striped occupation fails in EU4 and Vic2 as well, not just CK. It can be very difficult to tell what country is occupying where if two countries have very similar colors, or if a separated territory like an island is being occupied by a power that isn't right next door. It's telling that the supposed counterexamples supporting striped occupation graphics are always extremely simplified and would be unambiguous no matter the visualization, like those here:
and not the situations that might actually come up in-game such as those I mentioned that designers do need to take into consideration when visualizing data. It's also telling that these examples never use actual in-game showings and only use again very simplistic and highly contrast colors with no texture overlay as you would see in the actual game, nor do they ever use the zoomed in Vic3 overlay of the living map. A better case to analyze would be something like in EU4 a Scotland and Castile occupying each other's colonies in the Caribbean.
It says a lot that with just looking up Victoria 3 screenshots on google, you can immediately tell this is a Scandinavian occupation before you even figure out where in the world the screenshot is taking a picture of. That's simply not something you can do with striped occupations and shows the relative ease of visualization of the flag occupation.