When did the "music industry" start formally steering commercial audio PHY standards?

Characteristic impedance alone is all over the map, Apple apparently couldn't align its 3.5mm jack pinout with the rest of de facto industry, and form factor is just one of many inherent market differentiators.

Why? For DRM?

I remember it was called “the analog hole” that enables piracy, that was going to be closed by a future date, back somewhere between 2005-2015.

My fuzzy recollection is that the "analog hole" stuff was mostly pushed by Hollywood with respect to getting around encryption on DVD and streaming video (as opposed to music, where similar encryption schemes were foiled in the market by CD and MP3 already being good enough, if not outright superior to the "modern" formats), and that with the advent of HD content they eventually settled for analog outputs being limited to SD resolution.

Wait until they find out that audio can be reproduced with little or no generational loss, because there is always an analog signal (since that's the point of audio).

Actually they've already found out that streaming and subscription slaughters piracy unlike stringent regulations which promotes illegal activities

The only way to truly stop piracy is obviously to disallow all devices from playing any audio at all.