why aren't nfl employees allowed to say "nfl"?

[PackersFTW]

ever notice how you have NEVER heard an nfl employee (announcers, analysts) say "nfl" but rather they ALWAYS say "national football league". this is one of those stupid things that bother me. i think it sounds so stupid. the only thing i can think of is they don't want people to confuse the nfl, the nfc, and the afc. my problem with that is that if you are confusing a conference with the entire league, you probably watch about 1 hour of football a year, and thus the nfl shouldn't give a damn about you.