I was not talking about the hybrid champion, but the build diversity itself. I think that teemo build diversity is fine other than frozen mallet being such a toxic item. If you take away his build diversity when he gets reworked, a lot of the people who played him won't be happy since a lot of people either went ad or ap.
Ezreal is not a balance nightmare due to being hybrid, he's hard to balance due to not building any crit or having any aa on hit modifier (his q isn't strictly an aa).
Maybe making the hybrid counterpart (teemo being ad) should be kept slightly weaker than ap, but I personally don't think build diversity is bad.
I didn't play when ap tryndamere was a thing but his issue I believe was how high his ratio was. Yi's issue was probably how uncounterable his damage was with his Q.
I think Eve was fine as hybrid, but her play pattern was a bit off.
I don't know though, maybe my opinion is biased because I main poppy and I don't like going the general full tank build (I still like playing her when building full tank, but not as much).