Because without mods, people tend to be horrible to each other. Just read through the modlogs sometime, it's depressing how unpleasant some people choose to be.
"Unpleasant" is anything that strays outside a very small circle of behavior. Moderation is a force for mediocrity and an energy-suck. And doubly so given the people who seek the job. It's inevitable
You can hang out in unmoderated areas with people hurling slurs around at each other, personally I enjoy a more civilized experience where people aren't just trolling each other.
Edit: Ahhhhh, this is a new account. I guess you got banned and are now butthurt and whiny about it. Which tracks.
Yes, an area full of assholes is bad. But an area full of smug fellows like yourself might actually be worse. The average asshole seems less inclined to team up with likeminded assholes and call their group vibe "objectivity".
Why don't you share your previous username? Then we can see what got you banned and use that as a test case for "is Lemmy better with or without mods"?
I have yet to come across anyone sharing their username after they get banned. You see them in posts or comments "I was wronged!" but then they don't want to give their user name. Sure buddy!
You do realise that in the fediverse you don't have to have a mod, right?
You can:
run your own instance
create whatever communities you like there
have no mods in them
federate with the rest of us
No matter how much modding or even defederating any of us did, you would have the complete ability to say whatever you like and even see all our content.
All we could do is choose whether to interact with you.