Way to screw all players who don't waste time on multiple characters. :/
My question is what if I don't play any of my alts? Can the discount still occur on my main once he's a certain il and i'am upgrading a piece of gear with the same il?
So if you're a generally casual player with a horde of alts that doesn't do M+ you're unlikely to have any serious amount of flight stones and will struggle to upgrade. It seems the smartest thing to do is to try and just grab the 60/90 fast crests and 600ish flightstones on each character, which tends to come very fast since you get a lot of freebies doing the early intro content and then level 1 different slot of gear on each character so you main now has a much cheaper flightstone cost, since after that first wave of intro freebies, the rate you gain them tanks FAST
TLDR: Just get better gear on your main 4Head
The only people who wanted the flightstone cap are the ones who spam all channels with boosting services. Nobody in their right mind would want and actually enjoy a cap for those resources.