The only actual reason given in the article is that EFnet etc. suffer from netsplits – the remaining 95% of the text complain about non-problems (age of the protocol) and the fact that an infected computer is, well, infected.
So IRC would be perfectly fine to use if the company ran their own server, which is far from impossible. And while I’d prefer a XMPP server, this is definitely not a big problem.
