As adorable and beloved as Elmo is, he gets a fair bit of hate from hardcore Sesame Street purists. Some have complained that Elmo’s prominent status has caused some of the older characters (e.g. Oscar the Grouch, Grover, Cookie Monster, etc.) To have greatly reduced roles.
In it's FAQ, the Sesame Workshop responds to the allegations that Elmo referring to himself in the third person will teach children improper English by stating that this behavior “mimics the behavior of many preschoolers.” That’s right, preschoolers; you know, the age group that the show Sesame Street is produced for.