I've had blog posts do well on Medium but sink like a stone on those platforms. It's a very different proposition submitting to medium and having it shown to people who are likely to be interested over a day, vs self-submitting to a site like HN or Reddit and watching it sink like a stone because the few people who are likely to be interested aren't looking at that particular moment.

Not to mention the fact that if you self-submit anything to those sites people tend to take it as an invitation to eviscerate you.