it is even common to print to audio any outboard processing that you do in one studio simply because you will not have it available at another studio where you continue to work on the same track - i.e. if you patch an external compressor or eq or fx unit into the processing chain, you print the result to a new audio track so that you always have the sound applied to the original audio
and I have to reinforce wapitis statement about daws extracting midi data from an audio file - simple monophonic audio (individual drum hits and maybe solo instrument lines like bass or brass- or wood-wind and some single note string lines) can be converted to related midi data, but, in the main, it is a pipe dream pursued by many a PhD candidate to extract all of the data that an audio recording holds into a cognate midi file - most humans struggle with the task of doing the same thing when transcribing to paper or their instrument