AMD supports openGL just fine, but they aren't gracefully failing sloppy programming. The Nvidia driver tends to try and make "something you probably sort of meant anyway" out of your illegal openGL instruction and AMD fails you hard with an error message. That's no reason to blame the manufacturer.
Nvidia is hewing to the following:
In computing, the robustness principle is a general design guideline for software:
Be conservative in what you do, be liberal in what you accept from others (often reworded as "Be conservative in what you send, be liberal in what you accept").
The principle is also known as Postel's law, after Internet pioneer Jon Postel, who wrote in an early specification of the Transmission Control Protocol
Its generally a good idea in when implementing a standard, if you want people to use it. Slavish perfectionism is the bane of developers that has killed many a project.