Yudkowsky flirts with tautology in the title - "well-kept garden" has keep right there explicitly and "garden" implies a caretaker. So almost by definition a well-kept garden won't persist without intervention.
But also of course not all ecosystems are gardens; not all ecosystems rely on keepers who are external to the ecosystem. A normal forest is sustained by natural forces and the normal actions of its inhabitants. As much as possible I'd like a community that sustains itself rather than one that is gardened.
I think these "well-kept gardens" are basically the HOA's of the internet world. The property values may be high, but that doesn't mean they're good or healthy places to live.
When a forest is staying a forest, because there are some negative feedback loops, and no one gardens it, it is usually enough to have a couple of goal-directed agents with axes to change it into something else.
It's interesting to think about how apex predators are the keystone that propagates order in their ecosystem. For as long as humans have been aware of wolves, we have sought to eradicate them. After all, they kill livestock. They are immortalized in stories as a symbol of evil. Little Red Riding Hood. The Three Little Pigs. The Boy Who Cried Wolf.
Yet once we were successful in eradicating them, to our complete amazement, we found that the eradication of wolves caused the proliferation of all of these negative effects that would have been otherwise kept in check by wolves.
I think the key takeaway is balance. Everything in moderation, even moderation, and especially moderation of the Internet.
But also of course not all ecosystems are gardens; not all ecosystems rely on keepers who are external to the ecosystem. A normal forest is sustained by natural forces and the normal actions of its inhabitants. As much as possible I'd like a community that sustains itself rather than one that is gardened.