Interesting actually. Because...
I think if Essence Reaver was overpowered you would see it more on other champs it makes less sense on. It's not even that oppressive when you do see it built on it's own.
Nah I think it's just Ashe still being strong from s5 then getting compensation buffs because
were OP for a while. Sivir is just because they straight tacked on 100% crit dmg onto her ricochet without even tuning it (also a s5 world championship champion.... hmmmm~~~~) . Now it does hit for like 60% regular autos already... but still...
I'm pretty sure Ashe can operate just fine w/o ER. I still click to good old IE preferably.
HOWEVER. I had a thought that ER builds "outscale" strangely due to slot efficiency. They put more gold in the only six slots we have compared to 80% crit double zeal builds. If you notice all ER champs seem to do STRANGELY well late game.

VS.

The ER build is about 700 more gold invested. And while it has a bit less crit and attack rate it has more AD which is big. So I wondered do ER carries by virtue outscale almost automatically? Should I be building ER and not two zeals on EVERYONE if I had infinite gold late game???

I been meaning to test these item powerspike dps on a tank in a custom to get a feel. I never do tho lel. Do ER 70% crit builds automatically do more dps than the cheaper 80% 2 zeal build by virtue of having more AD/ more stats in their slots?