Because this is the first election where "spirit cooking" and "pizzagate" conspiracies were put on equal footing with foreign policy and economic positions.
>The supporters of Andrew Jackson began spreading a rumor that Adams, while serving as American ambassador to Russia, had procured an American girl for the sexual services of the Russian czar. The attack was no doubt baseless, but the Jacksonians delighted in it, even calling Adams a “pimp” and claiming that procuring women explained his great success as a diplomat.
Pizzagate had nothing other than fever dreams.
In contrast, all of the wars you talked about were based on real things. The Iraq war was started on falsehoods but the media was reporting what government officials were saying and attributed those claims to them. They should have been more skeptical, yes, but that's a completely different level of discussion compared to a bunch of trolls and gullible people free-associating completely unfettered by reality.