[bunderbunder]

If that's true, then incumbent Wikipedians need to take it upon themselves to communicate that to newcomers directly, and not in a random comment in Hacker News.

Probably the easiest way to do that: If someone makes a substantive edit that isn't obviously vandalism, but doesn't quite meet Wikipedia's standards, then don't just undo it wholesale. Instead, temporarily pull it off the main page and into a back-end discussion. And then immediately contact the author with an explanation of what's going on and what they can do to get the changes reinstated.