I have been on Lemmy for over a year, and honestly, Lemmy should be looking up to Reddit on the echo chamber topic, not down on them lol. Like, if you thought Reddit was bad with Witch Hunts / Block Sprees / Whatever other tactics to create an echo chamber, Lemmy makes Reddit look like it has the mose diversity of opinions and posts on the entire internet.
I first came here from Reddit. About 2 or 3 months prior to the API Shutdown, I deleted my Reddit account on my own. Wasn't banned, never had been banned, just didn't want an account anymore. Then I saw in a Discord server someone talking about the API Shutdown, so I went to read some posts on Reddit about it. This is where I saw someone mention Lemmy. They talked about it like this place that was open to any ideas, any ideology (obviously not disgusting criminal activity like CSAM, yes I was here on Lemmy for the CSAM raiding early on unfortunately), was not politically affiliated with any political group or government. Sounded great to me, since I don't care about politics and don't want to see it. I have to see it enough in real life and I just don't want to deal with that crap any more than I have to. Just Lemmy users talking about their niche hobbies or groups. Basically, I was sold the idea of Reddit without politics.
For the first maybe, 3 or 4 months, Lemmy was pretty good. Not politically infested, nearly everything was on topic, not a lot of bots or spam. Genuine conversations between people that didn't always agree but those conversations did not devolve into name calling or anything. Dunno what happened, but that Lemmy is gone.
And before anyone brings it up, yes, I am a Lemmy.world mod for c/cars. The LW Admins asked me to be a mod because I was one of the more active users in that sub, along with the other current mod. At first, I said no. I didn't want to be a moderator, and honestly I still don't. But after asking me more and me saying no more, eventually the admins convinced me to be a mod. Here's the thing: I have never had to take moderator action on anything. Don't know if I ever will because of how low traffic that community is. But my mod style is simple: I don't care if I agree with what is said or not. I only care if a rule is broken. Justice should not have an opinion, so when I need to take action I disconnect it from my own ideas and opinions. Kinda like what one is supposed to do as part of a Jury in the US Justice System.
Anyway, the point is, Lemmy and Reddit have pretty much become the same, because they are now both infected with the same basic problem. So I wouldn't say Reddit is worse than Lemmy or better. They both have pros and cons that make them more or less equal, just the pros and cons are in opposite ways. Perfectly balanced, if you will.