So I made a Substack account at tfos.substack.com exclusively for the purpose of having a landing page for people to go to if I comment on Substack posts. I left my first comment with that account today and subsequently got my first subscriber... and apparently it's counted as coming from the "Substack Network." This immediately brings to mind Substack's claim on their landing page that "around 10% of paid subscriptions to Substacks come from within our network." I previously assumed that meant the 10% was coming from recommendations. When I tried having The Sample do cross-promo via Substack recommendations previously, engagement from recommendation subs was 10x-20x lower than organic subs. So unless Substack says otherwise, I'm inclined to believe that most of those paid subs are being driven by comments rather than recommendations. I guess my conclusion is that setting up a shell Substack account just for comments is worth your time :).