Nerf Dark Harvest
Sorry for the long post, but I wanna be clear.
I've seen many complain and others defending it, but I don't think you can justify this rune. Let's take one quick look again at this rune and let's compare it if you do have it compared to if you don't have it. I will only use items since not all champs have the same stats and therefor can be used on any AD.
PASSIVE: Both enemy and allied, champions, large minions and large monsters within 1400 units drop Soul Essence on death, which you can collect for the next 10 seconds by moving nearby. If you kill the target yourself, the Soul Essence will be automatically picked up. Champions grant 6 Soul Essence; large minions grant 4 Soul Essence; and large monsters grant 2 Soul Essence. Select champion summoned units are classified as large minions.
Collecting Soul Essence empowers your next basic attack versus an enemy champion or structure within the next 20 seconds to deal 40 - 80 (based on level) (+ Total Soul Essence) (+ 25% bonus AD) (+ 20% AP) bonus Adaptive damage.
After collecting 150 Soul Essences you become Soul Charged, increasing the time to trigger the empowered attack to 300 seconds.
ADAPTIVE DAMAGE: Deals either physical or magic damage depending on your bonus statistics, defaulting to physical damage.
Let's take these items for example.

The amount of AD gained from this is 0+40+70+80+50+50=290.
Late game, AD's go well over it, but let's be generous and only take 150 stacks max. Then the trigger lasts for 300 seconds. So 25% bonus AD from 290 is 73 (72,5) + the 150 stacks + the 80 bonus Adaptive Damage.
This means you go from 290 AD to 593 AD and keep in mind, this is the absolute minimum we took for the stacks to trigger the longer empowered attack. This also ignores any extra damage taken with critical strikes (which also use this damage boost) as well as champs like Ezrael or Shaco who have skills that stack both AD and AP, getting the boost on both ends.
Now don't get me wrong, I am aware that for the comparison, I didn't use any other runes. My point however is to show how much DH gives you, specially late game. When a single Q of Ezrael does like 700 or 800 damage and you know it's only going to get stronger, maybe something isn't quite right? I've had so many times when I play as a tank and am up against an AD champ with DH, no matter how much Armor I stack, a single skill will take like a quarter of my health. And this is also ignoring any passives of the items, specially regarding armor penetration on top of that bonus damage.
I know it's long and boring but I genuinely think this needs a nerf. I believe the only reason that it isn't so prevalent is because it did get a nerf before and people claimed it was too weak. I think those who make that claim now have barely played against any Dark Harvest AD champs, especially on ARAM it's a disaster cause minions on both sides are always close. And seeing how Dark Harvest drops harvest individually for each champ, you could have 2 or 3 AD's with this Rune.
And if there was any more doubt, just look at some of the video's online. Q's doing like 800 - 1000 damage, people getting killed by a single Rengar Q (who is already overpowered as hell), where with his ult, you literally cannot do anything about it. The worst on this is snowballing champs because they get harder and harder to stop, making late games a slaughter fest for those up against these champs.
I wanna know what others think about it and please be respectful. I gave my honest two cents about it and tried to explain why I think this should be nerfed.