It appears that something has changed with the Friend Link since Casey wrote this article.

My friend is a non-paying Medium member, so she only gets the complimentary quota each month. If she opens a Friend Link after the quota is met, the Medium app on her phone does not let her read the full article and gives her a sales pitch instead. I have no reason to believe this is not happening with others as well.

For the small change that being part of the Medium Partners Program brings me, it makes more sense for me to take my stories out from behind the paywall, rather than confuse/irritate friends IRL and on social media who are trying to read me.