I have seen a lot of complaints regarding the perceived OPness of height advantage.

These usually claim that height advantage offers a to hit bonus/malus that is equivalent to a +-5 on dice rolls.

This is actually not quite true. Assuming an even distribution of hit chances, height advantage only gives a +-3.5 equivalent on dice rolls.
Proof:
https://www.wolframalpha.com/input/?i=sum+from+n%3D1+to+19+%281+-+%28n%2F20%29%5E2+-+%2820-n%29%2F20%29+%2F19+*100+%2F5

This kind of makes me wonder:
Do some people intentionally spread misinformation?
Are they just bad at math?

At least heigth advantage is not as bad as many people claim.