A bit of a pet peeve complaint for me. Maybe it's just me, my age or…

A bit of a pet peeve complaint for me. Maybe it's just me, my age or most likely the way I was raised, but how hard is it to say good bye when you are through chatting with someone or need to go? I find it extremely rude to just disappear without a word, especially when you are having a nice conversation with NOTHING being our of line or over the line! What happened to common courtesy?