Y'know, the more I'm reading this kind of thing, the sillier it's starting to sound to me. He's toxic because he forces you to change your playstyle? That's a petty reason to be annoyed by an enemy in a game. If anything, I feel more champions should be like that. Not having to switch up your playstyle just breeds complacency, and anything that breaks that up is instantly seen as a bad thing despite the fact that we should never be allowed to become complacent in a PvP game where every champion is supposed to fill in their unique role.
Say I'm playing GW2, for instance, and I'm in PvP. I don't get to approach any class the same as I can another. A Mesmer is going to confuse me to death (both literally and figuratively), whereas a Warrior is just going to brawl my face in, while a Thief is going to gank and use his mobility to make sure he never fights in a disadvantageous position, and so on - and that's not even mentioning whether or not they're going for a beat-your-face-in Power build, or a Condition Damage build, or a heavily defensive/supportive build. In DotA2 I don't get to approach Drow Ranger the same way I might approach Sniper, and someone like Anti-Mage or Spectre force you to change your strategy as soon as they're picked if you planned to bring it to late-game yourself. Even in Heroes of the Storm if someone picks, say, Medivh or Zeratul you have to switch up how you play the game because of what they do.
If only a handful of champions are able to reliably make you have to reconsider your strategy, that's not a good sign - that's a sign that everything is so similar it can be dealt with in roughly the same manner. "On many tanks and bruisers, you are forced to rush a Randuin's Omen if you are behind, whereas against any other AD matchup you could build Sunfire Cape and come out on top." That... that doesn't sound good to me. He's the only one that can force you to build differently, and so he's bad for that? Why are the others not able to put you on the back foot just because of the existence of that item? If he's the only one that can make you build differently, then we need more people that can do that.
I won't comment on Zed because his problem is largely the fact that he runs on an energy pool in a game where the majority of the roster is on a mana resource, which is an inherent issue that has to be balanced incredibly carefully, which is probably why I don't see other MOBAs even bother - some people might have no mana at all or run on fury, but nothing but League has you run on Energy.