I can't speak to US social media trends as I live in Europe. There is a certain overlap for sure, but I can't say I follow the online water cooler talk about current shows outside of this server. My critique was based only on watching the show.
You could have a point about changing audiences, and certainly about broadcasters lagging behind such changes. If the powers that be chase their own tail rather than connecting with the actual viewership, surely their shows suffer.
It surprises me a bit that Legacy of monsters reached beyond its target audience, though. It just doesn't feel very engaging to me. But I may be closer to the intended viewer rather than the people actually watching? Which again just emphasises the discrepancy between intent, expectation, and reality in terms of this show and its audience.

...and with Annalee Newitz as editor in chief. This could be good!