(However, as soon as the chance presents itself, I'd try to get said beginner away from PHP. That shit melts your brain.)
For eg, take the case of PHP arrays. If you are a beginner, you will probably have fallen in love with this thing. And when you show them a better language, and they finds out that it doesn't have arrays like PHP, they might feel very unsure about your claims that what ever you are introducing is the better language. If they have found /r/php, then it becomes almost impossible to convince them. You will have to counter the vague bullshit fed by 50 guys from /r/php to make any progress with the matter.
So while the author point about getting your feet wet is important, it is also important that you are not doing that be entering into a swamp that can suck you all the way down.