The post is preposterously absurd. We had fifteen million games older than WC3 that managed to create beauty and functionality without spawning one of the most cancerous art genres that nerddom has ever witnessed, and which has since destroyed everything it has touched. 20 years of bad D&D-and-friends art can be ascribed solely to WC3's artstyle.
The art style and the question of the graphics and the skill that went into making them are two completely separate issues.
I would also say if there is a problem with the art style, the blame should go on WoW rather than WC3, since the reason the latter used that specific style was precisely so you could
see the unit and tell exactly what it was at a glance (notice how Reforge just made everything worse simply by virtue of going for a more high detail, realistic approach). I would also argue it was an attempt to circumvent the inherent limitations of early 3D graphics.
That they then just used what was intended for an isometric perspective and used the same assets for a third person game is where they "legitimized" the style in the way you are describing if indeed that's what happened. I remember looking at shots of WoW and not understanding if it was a joke or not, since it literally felt they had blown up the graphics of WC3 and then even went so far as removing some of the shadowing on top of it. WoW only looked half-away decent in motion from screenshots it felt like Blizzard was literally taking the piss on us by taking us into the "World" of Warcraft 3 in a manner similar to Tron or some shit.