Reddit has always had a massive problem with misogynists, racists, pedophiles, etc. and the staff never does anything about it until there's media attention. They monopolized the web forum medium which basically forced communities to have to exist on that extremely toxic, hate-filled website.

I'd say I'm elated to see it go, but to be honest I don't think it is going anywhere. With any luck, Lemmy will become a vibrant community while all the assholes stay on the site they deserve.

Edit: Also, Reddit is designed to be addictive and has a reputation for it's negative, doomscroll-inducing atmosphere. Then there's the whole race-to-the-top karma system that ensures that Reddit has a monoculture where all the replies are predictable and similar.

Fediverse platforms aren't built around being addictive and in general tend to be more positive and diverse, making them feel large in spite of actually being significantly smaller than mainstream platforms.