I find Lobste.rs generally has more nuanced discussion about tech (and only tech, non tech stories are removed) and fewer hot takes, but it's also a heck of a lot "quieter" (i.e. much less volume of both stories and comments - the current #2, #3 and #4 articles on the homepage are 12+ hours old)
It also isn't intrinsically linked to the VC scene like HN, which may or may not be a plus/minus, depending on your views.
There are people on HN (or probably other sites, maybe Reddit?) who will invite "strangers", but typically we want to have some idea what the person is like, as an invite creates a permanent link (on the site) between the inviter and the invitee.
If the invitee turns out to be a spammer, or posts a bunch of hate speech etc, the inviter may be held responsible for the invitee's actions. This isn't a hypothetical, it's explicitly explained in on the invite form, and I've seen cases where people were banned because they invited people who then acted spammy.
Yea I understand the reasoning, but my general apathy prevented me from going that route - it was a "do I care enough about <topic> to go throuugh finding someone and convincing them to vouch for me?" type thing, and the few times I've wanted to comment, I've just given up.
I'm not against the invite-only system, having been a forum moderator for several years, but I'm happy to just be a consumer/observer of the conversation rather than a participant.
It also isn't intrinsically linked to the VC scene like HN, which may or may not be a plus/minus, depending on your views.