Well obviously some things can be learned from replication but mistakes are a better teacher since as long as something has not been researched (which is the most appropriate name for the learning process) the mind will still consider it possible because it has no memory of it being denied, it's like identifying what can and cannot fit into a box, even if we judge something is unlikely to fit in, as long as it is not obviously impossible (such as a regular keyboard fitting into a ring holder) it is better to try it to either confirm or deny our suspicions. It is more dangerous to leave a suspicion unchecked than it is to copy another.
No, mistakes are not a better teacher. Mistakes are an inevitable and essential part of learning, but making more mistakes on purpose by ignoring or defying available correct instruction to see if doing the wrong the works anyway is ridiculous.
The mindset you're describing is more suited to invention and scientific research and is useful there to never assume anything or take anything for granted and test weird apparent dead-ends, but in that case there is no well developed correct model so again... mistakes are an *inevitable* part of learning. That is in any case a very different thing from learning how to operate in a well-developed system (e.g., how to break down and rebuild and engine, how to perform a ballet, or how to speak a language.)
With language in particular, experimenting to see what might work also will gain you a ton of false positives - you can write or say many things that still manage to communicate in the situation at hand, but those things may be ambiguous and ineffective in other situations, or awkward and unnatural and require a very discerning recipient to understand you, or it may even be that you only think you communicated when what was understood was actually entirely different from what you meant to say. You can spend literally forever making and learning from mistakes in language learning and never successfully learn a language.
If, on the other hand, you learn from replication of correct examples, you will eventually learn the language. (Of course this does require enough quantity and consistency of learning to not forget faster than you learn. Studying one sentence a day or something will plateau far below functional use of the language).