Grammar training ineffective and rather harmful

Most of us know the standard way foreign languages are taught: very little direct practice (in German high schools statistically about 20 hours in eight years!), a lot of translations from one's native to the target language and lots of grammar drill.

The problem with this: it is not only about the most ineffective way of language training, some of these elements such as translations and grammar drill are outright harmful.
Before we get into the details, please consider this: how did you learn to walk? All by yourself I believe and further you might agree that nowhere in the world there is a pediatrician or pedagogue who would advocate special walking instructions and drills for babies and toddlers (unless they were disabled). Likewise we all know that children learn their native language automatically just by listening and gradually communicating with people who are more advanced than they. By the age of six a normally developped child knows about 100,000 words in their native language if you count all word forms, e.g. go -> went, brother -> brethren, may -> might etc. Even a professor who later teaches that language as his best foreign language will hardly ever surpass such a six year old which you can easily check by asking him or her for e.g. a list of thirty types of tree or thirty species of birds, or if he knows the games and toys such child usually plays with in his native language and is accustomed to name.

So we may safely say that nature's normal way of acquiring a language is the best, simply the most effective way and that all other methods lag miles behind. While there are a many fun ways to learn a language, they're still not as effective as the simple way babies acquire their first. But there are certain widely employed methods that are outrright harmful and one of them is grammar training.

Did you ever reflect on grammar when acquiring or using your native language until the age of six? Not really, most people whose parents are accomplished speakers just pick up their parents style and vocabulary. The most important thing though is that we have certain areas in our brains that are trained to distill rules from repeating patterns, such as past tense or the plural "s" as in manner -> manners, fan -> fans, can - cans etc. This process is automatical and the correct "grammatical" rule becomes woven into the language usage pattern and then works without thinking.

But if you force anyone, esp. children, to reflect upon those rules, worse even to learn them up front, then you destroy the rule building process and in the end your child may never learn that language properly but may always stay a self-conscious and slow speaker who always tries to first access the "rule book" now saved in a completely different part of their brain.
This is known since decades, however, modern school currikcula and teacher training does not reflect that knowledge. Rather children are given assignments in their native language and challenged to translate into the target foreign language, whereby they are asked to apply those cherished rules. This is part of a series of articles where we will also cover the harm that's done by forcing children to translate early between languages. Let's just quote a few sources on grammar drill and its effects:

"Why Doesn't Grammar Correction Work? The first reason why writing class grammar feedback doesn't work is that it treats only the surface appearance of grammar and not with the way language develops ... Secondly, learning grammar in a second language is a complex and gradual process which occurs both developmentally and hierarchically (some items are acquired before others). Compounding this is the fact that the learning of linguistic items does not occur in a linear fashion, that the learning curve for an item is full of valleys and peaks, progress and regressions." (Grammar Correction in ESL/EFL Writing Classes May Not Be Effective, Ronald Gray, Beijing Language and Culture University (Beijing, China))

"So what should a L2 writing teacher do? The quickest and most effective solution would be for writing instructors to simply stop making grammar corrections." And take note: "In short, teachers need to train themselves to set aside their red pens and examine ideas and see what students are trying to say instead of simply looking for grammatical errors."

"When you are just learning to speak a new language, learning grammar rules is not only senseless, but harmful as far as developing your ability to fluently express yourself. ... In most cases, our speech is formed by communication, the quantity and quality of studied literature, education, or simply our surrounding environment. During systematic simultaneous repetition, one develops an inner sense of the language, and the ability to imitate correct pronunciation of words and phrases."