Note that this is the admission policy for a per-blog whitelist - we're not talking about including *.substack.com as a "good" domain, just allowing someone to propose the inclusion of hacker-bob.substack.com.

And the policy already allows wordpress.com or blogspot.com (the latter is probably mostly spam nowadays, with a few holdouts who have been using it for 20 years). Also note that Small Web allows YouTube channels under 400k subscribers (!). So it's really not that clean-cut.

The social network seems relevant to me. It feels like people are posting for clout, trying to get to as many inboxes as possible, so they post a lot of marketing slop, just like on LinkedIn.