If you wonder why are they there and if they also spread bad information then maybe you should speak up about it and invite others to do so as well. Yes the tutorial above can be helpful to those who need it but it also has some bad information which needs to be fixed. If you do not want harsh criticism of your work, you are best off double checking your facts and possibly providing links to supporting material or actually pointing out where (what book, seminar, etc) you got your information from.