People are generally pretty lazy, uncreative and easily influenced - you show more of the exaggerated ideal on screen because society lacks imagination. They can handle little to no nuance.

So while I understand your frustration, there is also the reality that if you show that all people get disowned by their family, then you normalize/perpetuate that behavior even further (especially in less experientially diverse areas). It becomes and remains "one of the steps" of the process of coming out our meeting outed.

Basically, if someone comes out on a generic, middle of the road CBS TV show like the big bang theory or something... and the out character is building up fear about a pending negative interaction with the parent character, and the parent ends up saying, "we knew all along... And we just love you as long as your safe and happy" - well then that interaction actually imprints something on real life grandma in Missouri. She sits with that for a bit and processes, discusses a bit with friends at the salon maybe, and when her granddaughter, who she loves, tells her that she likes girls one day, grandma (who is caught off guard and doesn't have much imagination) reaches and finds that big bang theory moment as an example of what a "good grandma would do" and she repeats a version of it.

So again, I understand your frustration, but the above is (a portion) of the motivation to show those influencing "examples" in media.