Why are some people so rude on this site - should yahoo be banning them after 3 strikes?

Why are so many people so rude on this site...shouldn`t they be banned after a certain time...I am not a shrinking voilet by any means...but when you ask a reasonable question...there is always a few that think they are clever by either insulting you, using fowl language etc., etc.....spoils it for me.. maybe they should be struck-off after 3 strikes....what do you think out there ?