I think this makes way more sense than the OP. The OP seems like a leftist, so that's probably why they reached that conclusion.
But I agree, the real solution wasn't that a certain kind of witch was banned, it was that the various forms of witches could be quarantined. The Lemmy devs had no control over other instances using the platform to host stuff they disagree with (e.g. exploding heads was/is a thing), they did have control over what content was allowed on their hosted instance, which was by default the most popular.
The thing that saved Lemmy, imo, wasn't being leftist, but providing a separate space for the most extreme leftists (lemmygrad) and keeping the main instance pretty tame. The leftists could talk about leftist stuff in their instance, the right wing could talk about right wing stuff on their instance, and the main instance had the more moderate people. Sure, some crazy stuff appeared on the main page from time to time, but it was easy to write off as "that weird instance" instead of something that represents the platform as a whole.
Other projects didn't have that separation, so the early content was dominated by extreme views from whichever group felt motivated to join, and frequently that was far-right nonsense. With Lemmy, actual communists were quarantined by the nature of federation, and many instances blocked their instance, so there were a lot of places that didn't have that content that attracted moderates.
I'm actually working on my own Reddit alternative, and I'm trying to be extra careful in how I approach moderation so I don't repeat the same mistakes as other alternatives (happy to discuss if interested). Lemmy has done a great job, whether intentional or unintentional, and there are some great lessons to be learned.