Andrew,
No problem with what you say – just saying Adobe normalize inputs to a working color space, Premiere uses always rec709 gamma 2.4, historically default in AE was gamma 2.2 – now they added in AE a Working gamma with option gamma 2.2 and 2.4
So all I am saying is it’s best in AE to work in sRGB gamma 2.2 so your video in browsers or most applications look as intended (otherwise you will likely get a gamma shift on playback).
Pierre