Apart from being very prone to cliche, the problem with "X for Y" is that it's got so much potential to be indulgent.

"Linux of online learning" might convey meaning like "platform," "open," :big ecosystem" and "you can build a brand on top of it." But, it sounds like they are saying "Awesome & incredibly successful platform for learning."

That said, I still don't think it's meaningless, though I don't know how much conviction the people saying it have. Think of the different connotations you get if you replace linux with Windows or iOS.

Like mission statements or any other form of cliche it's bullshit & self indulgent 90% of the time. But if it's done with conviction, it can have (useful) meaning.