"Mail just works for almost everyone." doesn't mean that there isn't heavy filtering in place though.
A lot of people use web based e-mail (gmail, hotmail, etc.). I'd wager most others either use pop or imap from their providers; very few -- if any -- "normal" users have their own web servers. Very few "normal" users use IRC.
Besides, even if your home operator would allow all types of traffic, you cannot rely on that everywhere. Ever tried ssh:ing from the free wifi most cafés offer these days? Or the pay for use wifi you can find at most airports?