Preprints have a long history outside of medicine. They have, for example, existed in the physical sciences for several decades.
Preprints in medicine have seen rapid recent uptake. Many funders (e.g., CIHR) have updated their policies to be explicit about promoting preprints as a form of responsible dissemination, and to specify that researcher’s should report preprints on their C.V. when applying for grants.
Some institutions have also moved to recognize preprints as part of hiring, tenure, or promotion decisions.