Because they will ALWAYS listen to the vocal minority. That's how we got censorship in the first place.
Are parent's groups a majority of viewers? No they are an incredibly loud mouthed minority that is not even the demographic. But they talk an awful lot and who are companies going to listen to? The ones bitching and moaning a lot or the ones who are not saying anything at all?
Any SJW messages that are now required to be added to series, how about lewd conduct that only 10% or less of the population gives a damn about, how about feminist messages, or things considered offensive to LGTQ, or offensive to Islam. These are all due to overly vocal minorities.
Everything that is censored, removed, or recently edited is because of a vocal minority.