I'm guessing it was back ported to Android 4.4, so it probably hasn't been available quite that long. (Update: Nevermind, looks like it was in the initial 4.4 release: https://www.youtube.com/watch?v=zxHVeXbK1P4) But they've definitely been warning about the pending API change since at least 2019: https://www.youtube.com/watch?v=UnJ3amzJM94
The devs in the comments of that video do have some valid complaints about the added complexity of not being able to use the standard Java filesystem APIs anymore with the new permissions model, but still, it has been 6 years.