Fascinating that you feel like having discussions with orher people is tantamount to being in an echo chamber.
Here's the thing, Lemmy isn't a content aggregator. Lemmy-UI is, but Lemmy-UI is not the only front end to Lemmy. LemmyBB also exists, and it gives you a front end that looks like a phpBB forum. The API also let's people make other front ends, to suggest other uses as well.
Lemmy is just an ActivityPub user and group manager. There are lots of AP groups out there. Friendica, which looks like Facebook, uses them for their "forums" , and you can follow Friendica forums from Lemmy. Importantly, you can also follow Lemmy communities from Friendica, where they're indistinguishable from a Friendica forum. You can also follow chirp.social and a.gu.pe groups on here, which are third party groups for Mastodon and other Fediverse microblogs. They're full of people just having microblogs discussion threads, without titles and everything.
Lemmy is however we use it. It's all just Fediverse down here. But if all you want is to aggregate links, what do you need comments and non-linking posts for? Just use Pocket.