"quality" is something you care about if you want to virtue signal your professional or intellectual capability, usually as part of a monetization scheme. Hacker News cares so much about quality because this forum is attached to a billion dollar startup incubator, and for many people here their persona is business. Posting on substack is business for most people. Posting on medium is business for most people. "Quality" is just another kind of influencer culture.

Writing blogs shouldn't be about marketing and reading blogs shouldn't be about maximizing information density. The vast vast majority of blogs on the old web that everyone yearns to return to weren't "high quality." You were just writing about whatever, likely in a style that would get you downvoted on HN for being insufficiently substantive, and if you were lucky someone else might read it.

I wouldn't even call it "low quality" so much as "non-commercial."