What are the benefits of the output practice, namely, writing in English? Here I discuss one thing as a benefit. That is, by writing in English, you, a learner of English, enter the field of written English.

It is like you actually wield a racket in a tennis court as a beginner of tennis. Then you'll get interested in other players' way of wielding a racket, particularly in professionals' way.

Or it is like you construct and tune up a bike for you to ride. Then you'll get interested in others' bikes, how those bikes are constructed and function, etc.

Likewise, by writing English, you'll get more interested in every sentence native English speakers wrote, as an exemplar of English writing. You're thus more prompted to analyze English sentences, since you, a learner of English, know that you still can't write English at that level. By writing English, you prompt yourself to read English more.