The process of comunication has two main branchs, the passive and the active comunication. The passive comunication is compound by listening and reading, the active comunication is compound by writing and speaking.
Nowadays, after the advent of internet, there is a lot of information like videos, podcasts, books, audiobooks and so on. Its easier learn a language from zero. But, there is a although, all that stuff works in the passive branch, someone who is exposed to that content aquire some skills like auditive perception, grammar, vocabulary, all this is excellent but is not enough.
The process of comunication requires two individuals with abilities in both branchs, passive and active. At this point reapear a famous character that the internet cannot erase, the teacher.