I have seen on some IRCs people writing 'sudo rm -rf /*" etc. (not as advice, but as a joke,) but that person is always promptly kicked out and everyone in the channel tries to warn others.

The author's view is definitely too pessimistic. Most people on IRCs like Freenode aren't evil 'hackers' out to 'hack' you (this reminds me of an episode of Numb3rs.) Other smaller IRC servers can get rowdy, but I've yet to see that on Freenode et al.

I think much better advice would be to not randomly execute crap you see online without knowing what the program is and does, especially in root.