I don't think it's fair to blame Less Wrong for over-optimizing. Less Wrong is just a resource and can be used in bits and pieces. Just because it can be overused doesn't mean that it is a bad resource.
Thinking about it some more... perhaps they don't warn you enough against over-optimizing. Like you said, there's a ton of advice about how to optimize a plethora of things. If you're going to do that, perhaps it's your responsibility to sufficiently warn against over-optimizing. But still, despite the fact that it could be overused, I think it's a really useful resource if used appropriately.
Thinking about it some more... perhaps they don't warn you enough against over-optimizing. Like you said, there's a ton of advice about how to optimize a plethora of things. If you're going to do that, perhaps it's your responsibility to sufficiently warn against over-optimizing. But still, despite the fact that it could be overused, I think it's a really useful resource if used appropriately.