I wonder if it's people not wanting someone to play around with their setting and "ruin it."

They should take the approach some indie video game companies do with streamers. Often you'll see a game have a "Please DO stream and make videos of our game" with an implied (and make money off it) because it's free advertisement for that company. Among Us wouldn't be anywhere near as popular if streamers weren't allowed to show people the antics that can be had in the game.

It would be nice to see more creators have a collaborative mindset when it comes to developing a TTRPG