BBT and The Middle for example are owned by WB and stream on HBOMax ,it wouldn't make sense for those networks to promote properties any more that make someone else money.

You are right about New Girl though,it's owned by 20th century fox so they should have every fiancial incentive to try and keep a social media presence. Even if the show doesn't end up on one of their streaming services,the more popular the show is on Netflix the more money they can charge them. Not to mention the show probably works better as a binge streaming show then it did as a weekly network series during it's initial run.