I wouldn't take too seriously guidelines on pronunciation, unless they are clearly for a specific geographical region or cultural scope. Words are pronounced the way they are pronounced and the notion of "should" doesn't really have much force.
For example, I am a native English speaker, but from Scotland. I would not pronounce "parent" in either of the two ways given in that web page. Instead, I and many of my fellow countryfolk would say something like pay-rint. And we would ignore anyone who dared suggest that our pronunciation was not what it should be.
Note: That said, we would also pronounce the single syllable word, "film" as "fill-um", and the two-syllable "magnet" as "mah-gih-nit". So ah'd be careful takin' prih-nunce-iation advice fae the likes o' us! 😉