I think it's a good rune because since a long time melees especially immobile ones had troubles to kill tanks as fast as things like marksmen, and this made them unable to teamfight
Darius for instance got buffed in 8.4, but i still do not see him being able to teamfight above d1
with this rune everything changes, he can focus the frontline as an immobile melee and do fine without being too afraid of not dealing damage to tanks and getting kited by the backline.
will also use this rune, as a Mordekaiser main i will at least
people are overlooking too much that his Q has 660% AD ratio since it has already 360% ad ratio, and it's bonus damage on top of 3 of your autoattacks
60 AD is really good
and the convertion into true damage makes him just like Darius able to focus on the frontline