Nope, its inspired by the original hero skill system they designed for Warcraft III, which is a somewhat simplified system of the skill tree of Diablo II. The whole MOBA genre has all of Blizzards assets to thank for its roots otherwise without Warcraft III’s map editor MOBAs would’ve never come to exist. Actually…

And DotA itself was really just an evolution of a custom map for Starcraft/WC3 called Aeon of Strife (iirc).

Lol, you’re mistaken on the inspired by MOBAs part. Blizzard made the skills and Ultimate system originallyfor Warcraft III & MOBAs were inspired by DOTA, which was a custom game using the mapmaker of Warcraft III. So in effect, noone inspired. Blizzard but themselves.