This belief of sign language-interference has endured despite a long-standing lack of empirical evidence that spoken language-only approaches are more effective (Henner, Caldwell-Harris, Novogrodsky, & Hoffmeister, 2016; Humphries et al., 2016).
While we have continually learned throughout the program that it has been proven that sign language does not inhibit spoken language acquisition, it still brings me sadness that it was "forbidden" to use at one point because of the thought that the child wouldn't speak. It makes me wonder how many more parents would take the time to learn sign language and use it with their new born baby if the argument/theory of delaying spoken language was never brought up. My theory is that more people would have been exposed and learned sign language.