No, they were saying the practice is demanded by custom, which is precisely what de rigueur means. There is no organization of snobby Pythonistas etc mandating

No, they were saying the practice is demanded by custom, which is precisely what de rigueur means. There is no organization of snobby Pythonistas etc mandating that its members make fun of PHP, and even if there was, de jure wouldn't make any sense. Quite the opposite, in fact, since it was de facto required to be critical of PHP.