Well, yeah, that is indeed the reason why English is banned in such classes, and also why I was not allowed to speak English to those Syrian refugees. Although I was only involved in their training for one evening, I had to say it was rewarding work. To see how happy they were when they understood something about the Dutch language they didn't understand before.
The hardest part for me in English is that the language is not really phonetic, so it's kinda guess how to pronounce words in written text. That's how I got the pronunciation of words like "colonel", "recipe" and "mirage" wrong. Now Dutch is pretty phonetic, just like German, but grammar-wise these two languages can give you headaches where English is a lot easier, I tell ya. Most verbs for example only change in 3rd person single. "I walk, you walk, he/she walks, we walk, they walk". In Dutch that's "Ik loop. Jij loopt. Loop jij? Hij/zij loopt. Wij lopen" and in German "Ich laufe, du laufst, er/sie lauft, wir laufen, ihr lauft, sie laufen", that's quite some stuff to memorize, already. And the order of words is quite often far from logical, where English has a more logic approach to such things for me.
Indeed "feeling for language" can be easily compared to an "ear for music" or an "eye for art" etc. I've known people who had no rhythm and who had to study a dance act. Even when teaching them a measure has 4 beats (the song they hard to learn on at least had), it was hard for them, and they had to count constantly. Now I am a non-active and certainly not great musician, but still I have rhythm and I don't need to count the beats at all, and there too goes, you have that talent, or you don't. I once did take some looks at Swedish, where my feeling for language also helped me a bit. Of course Swedish and Dutch do have a lot in common, so I could relate to Dutch, but still I could see that Swedish suffixes words with an "r" or "er" to form plural. "sko" = "shoe", "skor" = "shoes", and that there's no word for "the" but in stead they suffix words with "en" or just an "n". "skon" = "the shoe" I don't think when you don't have "feeling for language" you'd see that, so easily. As such I immediately understood the US saying "close but no cigar", even though there is no Dutch variant to that saying, but what gets me though as when you guys say "drugs", as I always have to puzzle if you mean medicines or the banned stuff that does awkward things to your mind. Haha! :)