Platform link suppression

Social and search platforms algorithmically demote posts that carry outbound links in order to keep users on-platform, forcing distributors to relocate the link out of the main body (e.g. into the first comment).

grounded in: commit af797fd/47bc298 'linkedin: link-in-first-comment — strip body link (reach penalty), post feed link as first comment' in li_publish.py distribution path