The Souls community gets stuck on dumb theories because a video or post goes viral. It's the same reason why everyone literally worships a guy who memorized the moveset pattern of a boss, like that's in any way impressive or unique.

Actual good lore discussion exists out there - Elden Ring Lore Talk is a solid subreddit, and YouTubers like Tarnished Archeologist, SmoughTown, and Last Protagonist do good work - but the theories the general audience attaches to are baseless and ridiculous. The most offensive is the interpretation that the Greater Will and Erdtree are evil parasites with Marika as some sort of sympathetic figure, when the Greater Will is almost always benevolent while Marika is outright antagonistic at times. She's worse than Gwyn in so many ways; maybe the fanbase was more forgiving of her actions because she's a hot chick.