You've made this argument before, and I note that you've made no mention of velocities, accuracy or longevity of RWS brass as compared to your now much superior Norma brass. Yes, RWS brass is thicker, and weighs 270 grains on average compared to Norma brass that weighs 215 grains. So yes, RWS brass will use much less powder (2-3 grains) to achieve the same velocities at the same pressures as Norma brass will. The longevity of the RWS brass is also superior to Norma. Meaning you will get more reloads out of it @65K PSI than you will with Norma brass.
Apparently the only criteria you continuously mention is that thinner brass will hold more powder.. Well no shit sherlock....If you actually owned a chronograph and ran the velocities of RWS brassed 300 Win Mag loads you might have surprised yourself by reaching max book velocities with 3 grains less powder. Which in your mind is apparently a bad thing.....
Look use whatever brass you like, but don't bad mouth a brand of brass just because you don't know that brass that weighs 55 grains more than other brand might just need less powder to achieve the same goals. Relative case capacity is something every reloader needs to keep in mind, but you apparently were absent from class that day....