Dark harvest and why it shouldnt change

So im writing this post after seeing some of the champions using dark harvest in youtube. And its absolutely dumb. Im almost certain the rune will be nerfed very soon, but my question is WHY IN THE HELL DID RIOT CHANGE THIS RUNE? Im not going to say that the old dark harvest was fine and it didn't need any changes, but i believe a simple nerf would've been much better than what ever the fock this thing is. The reason riot decided to change dark harvest was "champions should not be able to 1 SHOT" Thus they reduced the damage to only be applied when below 50% health. The thing that riot doesn't realize, and it actually makes me very sad that they cant realize such a simple issue, is that no champion actually one shots. In fact its a fast usage of a champion's combo that kills the opponent which in term is known as "1 shot". What I'm trying to say is the new dark harvest doesn't solve anything, as a champions full combo will still most likely proc the rune with the same rotation they used with the old dark harvest. It has in fact even buffed the so known "one shotting" action. The other thing that i cant comprehend is why would riot even make this a laning rune? Champions who need to go for an all in inside lane such as diana or leblanc or zed already have electrocute as an effective rune for doing so and they were already doing great with it!! Adding dark harvest to another one of their usable runes isn't simply another option they can take in different situation, its basically a " You must take the rune that deals more damage and never use the other one" type of deal. Edit : The video ... https://m.youtube.com/watch?v=sGUFRcRchUA&t=7s