> Apple was the company that boosted OpenGL popularity by using it as the graphics API for OS X

Certainly they were a company that boosted OpenGL, but the company? During the early years OSX had less market share than Linux does today, and OpenGL was already well established by gaming and professional software before OSX ever came out. Quake supported it (not on release), Quake II and Half Life supported it on release, Quake III required it. Heck, Quake III released on Linux shortly before MacOS (classic), making it arguably as influential then, and of course the OSX port of that only came a few years later. But point is, that Id dared to release their new flagship with only OpenGL support shows that OpenGL was already firmly established and supported before OSX existed.

Yeah, I would say id (in the quake era) did far more to keep opengl alive than Apple.

Without quake and a few other popular games, it is likely direct3d would've been the only thing supported by non professional graphics cards.