It is a play on John Lennons' and Yoko Onos' song [1] and in my personal opinion it conveys the content of the post much better than a simple "PHP sucks", because we are all used to hearing that all the time, and the post is not really about the suckiness of PHP itself, but rather prejudice against it and the people who use it in the dev community.
[1]https://en.m.wikipedia.org/wiki/Woman_Is_the_Nigger_of_the_W...