I found some interesting perspectives on the history of music publishing in a book available online: Music Publishing in Europe 1600-1900, by Rudolf Rasch. Mechanical printing techniques for music were first developed in the 15th century, and by the 18th century engraving was the dominant process. This century saw quite a difference in the way that composers earned their living – instead of being supported by patrons and being tied to a particular Royal court, they started to rely on publishing for their income and became more independent (though now at the mercy of publishers who would ultimately decide what was worthy of being printed). Publishing houses became bigger and started to collaborate with growing numbers of shops across Europe to disseminate printed music.
There seems to be evidence that the availability of published music encouraged the development of musical literacy in the general public, leading to more domestic music making. On the negative side, it’s possible that it contributed to a decline in aural ability as people no longer needed to learn music aurally. Perhaps most importantly, composers’ works were able to be played and heard within a much wider radius than before, and musical styles began to cross borders. It would be interesting to research how the performances of works changed when the composer was no longer on hand to instruct how they should be interpreted – I think this led to a need for more explicit notations rather than relying on conventions.