You may have been listening passively for 6 years, but HOW INTENSIVELY? (how many hours per day EVERY DAY)? Students in the ALG program, on average, go to class 3 hours per day every day for a year before they start speaking – that is, they listen very intensively over a relatively short period of time.
I’ve found that after only 60 hours of listening to Mandarin (an hour a day every day for 2 months), words and phrases are starting to just ‘pop’ into my head without me even thinking about them. I’m certain that this type of ‘thinking’ is not detrimental, as the words and phrases just ‘rise to the surface’ and you’re not yet trying to say them out loud. The ‘thinking’ the article refers to is trying to ‘come up with’ language (whether it’s grammar conjugations or vocabulary) instead of just drawing on the vocabulary base (which INCLUDES grammar) you’ve acquired from listening.
I do believe that words and phrases will come naturally if you listen INTENSIVELY and wait long enough to start speaking. Just ask Steve about his experience with Russian, which I’ve heard native speakers say he speaks very well – check out his video and the comments here
Notice that, although he has to think about what he wants to say, the words and phrases seem to ‘flow out’ quite readily, an obvious sign that he did lots of natural listening to the language before starting to speak to any great extent. And, although he may make some mistakes with grammar, remember that native speaker children ALSO make grammar mistakes (‘I goed’ instead of ‘I went’ etc. – confer Krashen’s Principles and Practice in SLA) and yet they still come out speaking fluently.
I think that, once you reach a certain level of understanding (ALG posits about 80%) after CONSISTENT and INTENSIVE listening, you’ve already established a solid pronunciation and grammar base, at which point it’s just a matter of activating your passive vocabulary (which, once again, INCLUDES grammar like conjugations and endings etc.) while continuing to augment it, which is what Steve says he started doing after about two years of learning Russian.
Finally, consider that adult native speakers also make grammar and pronunciation mistakes and yet we still think of them as ‘fluent speakers’.