They aren't talking about swear words, they are talking about swearing on things such as Bibles and the name of God.
I choose not to say "omg", or to use the name of God at all unless im addressing him, but thats just me, it makes no difference to me if other people do or not, its just a personal choice.
Also, once again with that link, people are to busy worrying about what they can and can't do and trying to figure out ways to point out others doing wrong, they fail to understand that legalism cant save them, so why get lost in it?
If you are truly saved and have Christ in your heart you will do whats right by Christ living through you and giving you a new heart being born again in spirit. No amount of studying what you should and shouldn't do is going to change a thing without true repentance twords God.