Everyone was thinking "it was a controlled demolition" or talking about Lazer beams, trying to explain that the plane was edited in, maybe the towers never even existed and were invented by the media. But in reality it was a lot simpler, the Saudis sent people to fly planes into towers. Was the "jet fuel can't melt steel beams", like, purposeful misdirection or were conspiracy theorists just too imaginative for their own good
There's been a lot of writing on why people believe conspiracy theories like that. Believing that there was an elaborate plan involving the government shooting lasers or whatever actually makes us feel more comfortable---if it wasn't the government, if it wasn't like something out of a movie, if a bunch of randos can just get together and do a terrorist attack and have such a huge influence on all our lives, that's terrifying.
There's some irony there, in retrospect. There absolutely were shady connections to be made, and lies told by the government in the aftermath. But the truth was more mundane than the wild conspiracies.
To be a bit conspiratorial myself, it reminds me of a plot point in the X-Files, where the government tacitly encouraged wild conspiracy theorising about UFOs, etc, as a way to distract from the more mundane, actual shady/secret/illegal things they were doing.