I agree.. BUT, i think it's important to also remember that for-profit like Reddit will have incentives to drive engagement patterns which can sometimes (i'm being generous heh) be toxic to the social atmosphere.
Opensource implementations have a chance to change interaction that is more favorable to the user, to the community, etc. I don't believe Lemmy or Kbin offer much here, yet, but Tildes.net talks about this and makes an effort there.
I'd like to see a federated instance that puts more effort in this space. It won't be what Redditors want.. because, well, Reddit built addictive patterns and this is the opposite of that. But nonetheless i think we can make progress on Reddit-likes when we carefully analyze what ramifications Reddit features have.
Yup, it's like email but take away recipients. Yea, there's sorta recipients, but you don't really know who it's federated with/etc. We (foss devs) need better optics here. UX is difficult, though i welcome ideas.