Human brains do experience in-group reinforcement, so we ought to aim that reinforcement at something like truth-seeking, which tends to encourage meta-level discussions like this one, thus helping to immunize us against death spirals. Note that this requires additional techniques of rationality to be effective. Consider that some truths--like knowing about biases--will hurt most people.

I never drank and drove, never drank, never tried a single drug, never lost control to hormones, never paid any attention to peer pressure, and never once thought my parents didn't love me.

This line is confusing in an article about "being mature" being an unnecessary and even counter-productive to self-development and rationality. Why did you even mention those? Did you want a pat on the back? Do you feel you met the requirements of being a "mature child" by not doing those things? That seems like the exact opposite of the rest of the article. There have been many posts on LW about how biases and mental structures "linger" long after we have quite believing and embracing them (usually referencing religious belief), and it seems that is what was happening here. You have inadvertently classified those activities as being "stupid teenager" activity, or to rephrase it "immaturity", despite having rejected maturity as a good means for identifying correct, moral, or rational behavior.

People of any age may try drugs, may abuse drugs, may use them recreationally, religiously, medicinally, under peer pressure, in order to impress or meet initiative requirements, or even to commit suicide. There is rational and safe drug use (emotional use, hormonal response) as there is irrational, dangerous and addictive use. As Anonymous_Coward4 already mentioned, the majority of the "drugs" and behaviors you mentioned are completely culturally constructed, and you might be seen as a drug-user (or even abuser if you're a constant smoker/coffee drinker) or hormonal, or angry/depressed based on a particular group's demarcation. What demarcation were you using that you brought this little quip in as a point? It seems like you are grouping those actions under a common node....that of immaturity, to which I'd point you back to your article (minus a sentence) to explain why that's problematic and undeserving of recognition or compliment. In fact many of those things mentioned in that sentence say more about your privilege than your virtues. Many people are forced to drive, even if they wake up not-quite-sober, because they can't afford to miss work, or let their kids miss their school/events; many people actually have parents that don't love them (and strong empirical evidence to prove it, sometimes beat right into their flesh); as for the peer pressure immunity, sorry but I'm going to have to call bullshit. Do you mean that you didn't go to the popular kids parties, didn't join the football team, and didn't socialize much? That's a whole lot of people, and you may have avoided some peer pressure, but it's just because your peer pressure was coming from somewhere else (like your parents, role models, and smart friends/teachers who (whether you admit it or not) helped push you to think more critically, pushed you to "be the best" rationally, and to be able to "win" arguments). Even if all of what you said is true, it really isn't noteworthy, unless you can show how it makes you more rational, moral, or efficient, rather than "mature for your age".

You quoted this:

A better response to a mistake would be to reinforce the effort: "Good effort! You're almost there! Try once more."

and previously said of the larger passage:

Now that we all know this, shouldn't we abolish downvotes?

But when you tried it out:

Alicorn,

Good effort, you are almost there

this was her response:

Good effort, you are almost there

...

Dude. Subtlety?

Didn't work. Shall I praise your effort and urge you to do better next time? Would that work for you any better than it did for Alicorn?

It's such a glaring fallacy, yet oddly it even sucks in religion's detractors. As if we could demolish the entirety of a poorly-connected religion just by overturning a few of its claims.

But of course, if you can't test many of a religion's claims, but those you can test have a tendency to be simply wrong, it suggests that the say-so of religious dogma shouldn't be enough to accept the others either.