Did you read the post you linked? It talks mostly about legacy problems. OpenGL 3.0+ is fine. And by the way, the emphasis should be on cross platform.
Well, the post claims that 3.0 was a failure, but I think that was a case of speaking too soon. My limited understanding is that yes, since then OpenGL has had much better shepherds.
The failure it is talking about was codename "Longs Peak", a project that was supposed to be OpenGL 3.0. It was supposed to be a redesign from scratch but was eventually abandoned and OpenGL 3.0 was based on the old GL 2.0 API (with some parts deprecated and some new things added).
Wolfire Games, of Overgrowth fame (they also were the original organizers of the "Humble Indie Bundle") have another writeup comparing OpenGL to DirectX. Their argument centers mostly on the market ("Linux users are important") and it's a bit dated (2010), but still a great read.