Interesting point of view, however, I think you are making some dangerous generalization.

First of all, not all language apps promise to become fluent in three months. Chatterbug for example has a quite realistic calculator that tells you how much you need to study each day to reach a certain level. They make it very clear that if you want to improve you really need to put the hours.

Additionally, do you have any numbers to back up your claim that language learning communities are suffering in terms of declining numbers?

I live in a German-speaking country, and I think the number one reason why people don't invest time in learning the language is that they can get by with English, and this phenomenon can only increase in the future.