It's due to them all watching Gravity Falls, Adventure Time and Steven Universe in their teens twenties. Those shows all had an episodic structure with an overarching narrative, "deep" lore that fans could speculate on, quirky homosexual bipocs and episodes with "mature" themes and jokes so manchildren can excuse themselves watching it. Except all those shows had competent studio oversight and were written by people with a professional animation background and education (even doe it's CalArts). The only show I've seen that bucks this trend is Smiling Friends, and that's due to the creators actually playing to their strengths, instead of trying to depict the realistic and messy breakup of an aroace polycule.
In short, OneyPlays supremacy