Here’s the idea: If we provide students with enough comprehensible input, the vocabulary and structures they are ready to acquire must be present in the input. This means that we might not have to make sure that they are there: we don’t have to deliberately focus on certain points of grammar given enough comprehensible input.
Just give students lots and lots of comprehensible input and they will acquire and grow substantial grammar and vocabulary and their overall language competence.
So one of the primary goals in acquisition-based teaching is to first focuses on providing students with abundant comprehensible input for building a solid intuitive (mental) capacity of the language which enables them to produce the language fluently and accurately, rather than immediately embarking on language production (speaking and writing).