The internet, they say, "democratises" human activity. We no longer need to go to the ivory towers of academia to learn; we no longer need experts as intermediaries: we can collaborate with one another.
This is true, certainly, but with it comes a certain set of dangers.
First, the "wisdom of the crowds" is generally fallacious, and we either get a mass of people who constantly contradict each other flat-out or we get little cliques that share and reinforce each other's views, to the exclusion of all new information.
More importantly, though, people want to defer to experts. This means that it's actually quite easy for someone with the right patter to set themself up as a "lay expert". Once they do so, they gather a little clique of the "wisdom of the crowds" type who will support and propound the self-appointed expert's proclamations.
There are many such "experts" in language learning. Typically they say they teach not on "dry, academic grounds" or the "received wisdom of the establishment", but "from experience". Their argument is simple and appealing: I have learned a language, therefore I know how to learn a language. But wait... haven't millions upon millions of people learned a language too? Why you and not them?
I call these people "professional language learners". Wouldn't we all like to learn languages as a job? Wouldn't that be great? I know I'd love it... except that's only of benefit to me, so really there's no reason for anyone else to pay me to do it. I find it difficult to stomach that there are people out there who make their entire living by writing and making videos about their language learning, and kidding themselves and their audiences on that they're giving some immensely valuable and unique insight into the learning process.
But they're not.
Their advice is at best vague, and very often even inconsistent and self-contradictory (eg Sid Efromovich's video that I discussed recently). Vague advice can be followed to the letter, and still have you doing something almost entirely the opposite of what was intended. As advice it's at best useless, at worst detrimental. Why am I failing? What am I doing wrong? Frustration sets in. Maybe I'm just no good at languages.
But why is the advice vague? Is it a fault in the author's use of English? His writing composition? Maybe, but mostly it seems to me that these people don't actually fully understand their own process. There is much to be learned from these people, but only if they're willing to discuss it, so that we can help each other tease out the details.
This is why we need to defer to language learning professionals, people who have trained, and studied, and (hopefully) taught. But most importantly, they are in a position to experiment. They can try something on one class, identify the weaknesses, then try it on another class in an adjusted form. Did it work better? Then it's better. A professional language learner only has a sample of one, and therefore cannot identify the changes that make things better.
That is not to say that all language learning professionals are always correct; sadly, language teaching standards are pretty poor at present. Many teachers and academics continue to parrot outdated and/or unproven theories as gospel, but if they can express their views more clearly, then at least you'll be better able to follow them if you choose to.
Of course, a lot of language teachers aren't really experts anyway. Most professional teachers of English as a foreign language have a four week certificate that is essentially a walk-through of typical classroom techniques, and no real in-depth analysis of what works, when it works, why it works or how. Simply being a teacher does not make you an expert, and very few teachers would ever try to claim otherwise. A real expert is someone who has dedicated multiple years of their life to both academic study of the topic and real life application.
It takes a lot of time and a lot of money to become an expert, and for those of us who are going through all the slog of trying to become genuine experts, it's kind of galling to see these guys walking the easy route and getting pretty handsomely rewarded for it.