By kicking out everyone they don't agree with over time they curate an echo chamber of the few that they do speak for.

True, but they are the ones with all the power. I think you’re fighting not just an uphill but an impossible battle. With very little upside to you if you win.

It takes about 10 seconds to create a new Reddit account so it's the moderators who'd be fighting the uphill, impossible battle to keep someone banned.

Reddit provides tooling to identify people on new accounts that have been banned in the past. I think you'd need to couple this with a VPN

Not true. Only admins can see alt accounts(based on IP address), and they never reveal alt accounts of others to even mods.

I've had new accounts banned for participating in subreddits where old accounts had been banned

Speaking as a Reddit mod, it's often possible to identify ban evaders through their use of language.

This was a very large subreddit and my new account had very little content at the time

VPNs dont matter anyway. Just make a new account. Unless you have some topic you constantly focus on, or have a tag line you repeat, you will be invisible.

This is not true (speaking from personal experience)