Keep in mind that inviting strangers to the site carries risks. After being an active member on the site for about a year - and liking it - I sent out my first ever invite for someone I didn’t know personally, but who seemed to be alright based on Twitter. That person was promptly banned for self-promotion [1], I apologized on behalf of this person I didn't know but invited [2] and was subsequently banned for having sent the invite [3]
Making it hard to get an invite, and not inviting strangers is by design, as I understand.
[1] https://lobste.rs/u/sebastienlorber
[2] https://twitter.com/GergelyOrosz/status/1295409271119765504