When you're the less moderated alternative to a popular platform, you end up with a huge fraction of the users who got banned from that platform.

For the most part, average people do not want to talk to the people who get banned from mainstream platforms. People who post images of children in bikinis described as jailbait are creepy. People who advocate political violence are scary. People who share shock content are disgusting.

Perhaps you don't make exactly those value judgments, but most people do. They will avoid your platform because it's full of people they don't want to talk to or hear from.

It's important, but so is community building. Most communities function best when there's some degree of moderation. For example, people would prefer that the speech in their bird watching community is limited and trolls are kept out. Putting up with abrasive behavior in your community isn't brave, it's just masochistic.

It is true that some communities on Reddit weren't possible because they were not permitted to allow some of the content they were allowing.

I have come to understand that due to rhe paradox of tolerance some form of moderation is absolutely necessary for the long term health of a community:

"The paradox of tolerance states that if a society is tolerant without limit, its ability to be tolerant is eventually seized or destroyed by the intolerant." https://en.m.wikipedia.org/wiki/Paradox_of_tolerance

Another way to frame it in terms of moderation is "in order to maintain open tolerance, we must be intolerant of intolerance". Ironically it was a Reddit thread that helped me understand that tolerance is a social contract: once one side breaks it, we need not be tolerant of them any more.