Learning a new language feels like hard work. And that is how it is supposed to feel.
You learn best by putting yourself in difficult, awkward situations. You wish to express an urgent need, but are unable to find the right word. You are forced to read somebody’s mind based on what they are saying. You communicate under strain. The tension of doing all of this overcomes your fear of making mistakes.
Our brains are lazy, and until we can trick the brain into perceiving a situation as a crisis, we don’t activate our most effective learning centers. The strain, the effort, the ambiguity, and the embarrassment are all stimulit that trick our brains into learning something new.
One drawback of modern design is its fetish with convenience. Modern language learning apps are designed to strip the learning process of all discomfort. There is no strain, no fear and no ambiguity. There is also no prospect of public embarassment. That is why most of them are slow and ineffective when compared to direct immersion.
Most modern design is aimed at reducing friction from a user’s behaviour. But with learning apps, this can be taken too far.
PS: An app where this flaw is particularly prevalent is Duolingo. An app that does a great job of avoiding it is Anki.