In addition to the reasons suggested in several of the comments here so far, the philosopher Giorgio Agamben is extremely critical of the concept of human rights since they are a legal and political construct, and the same legal and political systems are used to create ‘exceptional’ circumstances in which the rights are deemed not to apply to certain groups. Relying on these rights is flawed, in his view, since they will be suspended when most needed. The Philosopize This Podcast did an episode on this just recently.