A complete profile makes recommendations more useful and gives people enough information to decide whether they want to connect.
The 80% threshold is an account-readiness step: until your profile crosses 80% complete, you are not yet eligible for broader network recommendations. The weighted fields are display name, bio, birth date, birth time, birth place, gender, intent (what you're looking for in connections), and locale or comfort radius. A profile photo is optional and does not count toward this percentage.
Why 80% and not 100%? Because some fields are genuinely optional and some users prefer privacy. You do not have to disclose religion or community to participate, so those fields do not gate you.
A complete profile also gives recommendations and relationship context more useful information about what you are looking for. Sparse profiles provide less to work with.
If you're stuck under 80%, the profile page shows you which fields you're missing. None of them require disclosure of anything you'd be uncomfortable sharing.