Pirate pioneers!

So wait a minute. Lets say that you found out way to kill Horntail in one hit. It would only be a glitch if you told other people how to do it (and thus everyone started doing it as well)?

It's a glitch if you play the game in a way not intended by the creators and this way of playing is giving you benefits you shouldn't be getting. It's a bug if it doesn't harm you or negatively affects you. That's roughly how you should look at things in MapleStory. Bug doesn't ban you, glitch bans you (if abused).