It's not a question of whether or not the league system is a good idea. If you want legitimacy in 2-player battling, then that's currently the only way to play.
There are things called rematches you know... Also, preparing to block all icon types was never a problem. GFD has existed long before the elemental swords and it was never dominant enough to make people think shields were useless.
Anyway, back to my previous point. It's not that hard to prepare your set to come out on top of at least most of the swords. Having a Pteri beats the Air sword. J-ring has always been a good weapon because it could come out on top against PCC, now it also beats SoWL as well as the light sword. Having an FTab takes a respectable chunk out of the fire sword and owns the water sword. That's already 3 slots devoted to beating 5 swords. A bomb and a healer/CBT will take up 2 more slots, leaving you with 3 slots to either deal with earth or find a way to break even with it (PCloud is an excellent choice). As I said before, you're not trying to do turns that "blocks perfectly", you're just trying to have the edge damage-wise.
i admit it is possible to theorycraft your way to a perfect scenario against any set. now you just have to use the right blocker on the right turn every time or hope they don't use anything but the same two HT swords every turn
KLens is still terrible as the absolute best case scenario for it is that you come out even.