Title of the article is seriously flawed. Every textbook and every respectable course spends more time criticising Stanford Prison Experiment more than discussing its results.
The text of the article contains evidence which supports the title's assertion and contradicts your assertion that "every textbook" criticizes the experiment. Do you have evidence to support your assertion?
> So, have the important criticisms and reinterpretations of the SPE been documented by key introductory psychology textbooks? Greggs analysed the content of 13 leading US introductory psychology textbooks, all of which have been revised in recent years, including: Discovering Psychology (Cacioppo and Freberg, 2012); Psychological Science (Gazzaniga et al, 2012); and Psychology (Schacter et al, 2011).
> Of the 13 analysed texts, 11 dealt with the Stanford Prison Experiment, providing between one to seven paragraphs of coverage. Nine included photographic support for the coverage. Five provided no criticism of the SPE at all. The other six provided only cursory criticism, mostly focused on the questionable ethics of the study. Only two texts mentioned the BBC Prison Study. Only one text provided a formal scholarly reference to a critique of the SPE.