As is Mr Raymond, to whom Mr Stallman was replying.

Another HN thread pointed out a subsequent email in which Mr Raymond realised that the GCC compiler did in fact have a sort of plug-in system.

RMS is far more knowledgeable, accurate, and respectful when discussing people he disagrees with, than almost anyone else is.

(People he disagrees with in the open source world, like ESR/OSI, who he considers neutral or incompletely free. He isn't respectful of people like Bill Gates who promote actively non-open software)