[frenchy]

> Even native speakers of a language need to be taught the formal rules if they're to speak well.

Native speakers are taught some rules, but many are rarely taught unless a student has learning difficulties. The adjective ordering that OP mentions is a solid example. Others include aspiration of stops; voicing assimilation in words like "bets" and "beds"; the difference between "putting up" and "putting out"; why it's (sometimes) okay to say "Hey fucker" to your best friend, but not to your teacher; and the deletion of nominative arguments in subjunctive phrases.

Second language learners often (maybe always) find more rules useful, for several reasons. However, those who learn the language in highly rule-focused manner often have difficulty actually communicating in the same way that Computer Science professors are sometimes quite knowledgeable about CS theory, but unable to produce good code. Rules are good at telling you what not to do, but bad at helping you be creative.

[mikeash]

Yeah, native speakers won't typically be exposed to the same rules, and there aren't a lot of rules taught, but they are there to an extent.

I wouldn't say that one should learn in a rule-focused manner, but neither should one learn completely by example. A mix is best, even when your goal is to have the rules fall away in the end.