No, I didn't. I just don't want to get caught up in your points because they don't matter to the issue at hand, but since you are being so frustrating with your sidestepping of the issue, I guess I'll just have to painstakingly go through this.
1) Did you know that daggers are generally the more effective weapon for Void Assassins? Did you know that you don't use the Main Hand for anything but a weapon? Great. You don't need that sword. "But the sword skills!" No, this is besides the point, it's not important to this topic and to what I'm even talking about. As you saw in the math, Elemental Resistance is an effective component against your enemies. "But you can't resist everything!"
Well, actually, thanks to things like Stamps, Sayakana, CoMCs, Talents and all manner of other equipment. You pretty much can resist just about everything your opponent can throw at you. Elemental Resistance alone or even paired with just one thing wouldn't really be a big issue but because of stacking it is a problem.
2) No, I didn't forget. I'm perfectly aware that Evasion and Guard work against each other but you are giving your average Evoker's accuracy far too much credit. But alright, if you really believe you can't sacrifice that 10% against an Evoker that relies on it's spells, guess what...?
You can choose not to Guard. It'd still be worth getting a shield for the Elemental Resistance. Here's another suggestion. You can use a Nullstone Gauntlet or alternatively an Ogata's Waraji on your feet. Or both. I can ramble on about this for ages but it's not important because the real issue here is the fact that you can stack it up so heavily, have multiple reductions trigger at once and make your attack nigh useless.
3) "Most classes" being unable to do it is does not mean it is not an issue now and won't be keep being an issue down the line. Think back. Do you remember long ago when the vast majority of players specifically used BK/Ghost for Wraithguard, Indomitable and Body Guard? Do you remember how Wraithguard was nerfed to specifically not work with Heavy Armor because the combination was so effective?
Don't keep telling us that stacking damage reduction is totally fair because the facts and the history show otherwise. The big difference between now and then is they are slightly less potent individually yet more readily available, making stacking several things at once easier than before.
So here's how this behaviour hurts all classes. People are encouraged to do the same thing because it is the most effective at defeating other classes. The best way to generally deal with it will end up being to fight fire with fire and then it becomes dependant on who has the best stats and equipment over using strategy to overcome your opponent.
Those that cannot fight on their terms will lose because they cannot reliably harm them and that means if you can't hurt them, you can't win and that's an issue for everyone. Maybe they can counteract one or two of their methods of damage reduction but you can't possibly stop all of it, some of these methods don't have counters in any way. And even better still, sheer defensiveness isn't the only thing they can possibly do.
This is the last thing I'm going to refute on this topic because this back and forth could go on forever and nobody wants that. You've said your piece, I've said mine, we clearly disagree with each other, let's just stop.
TL;DR stacking damage reductions is a glaring issue. Even if the new Evasion skill is nerfed (and in my opinion it should be), there will be new items, skills, etc. in the future that will fall into similar trappings and will need to be addressed. I think it's a good opportunity to deal with this now.