I know some think that, I don't however. Kids 8 or so and under just think differently. Kids under 8 thinking the moon follows them around, that Santa is real, etc., doesn't mean they will think that in 5 years let alone their whole life. I think creating an environment where kids - regardless of age - are told some things are bad, that can linger forever and is harmful. But sometimes having them be accepting of things they don't even know exist (let along have an opinion on) may be a problem as well - even with the best of intentions. Once kids hit Grade 5 and middle school, I think all topics are fair game.
There is a famous story about how Sesame Street wanted to do a show on divorce, and the whole point was to try to address the fact that kids often blame themselves in a divorce and also to show that divorce was normal for some kids - so the thrust was reassuring Big Bird that the two characters (Susan and Gordon maybe?) that were getting divorced were not doing so because of him and everything would be fine. The test audience of the kids never got that - they agreed with Big Bird's initial though he must have been at fault. They never aired the episode.
