I recognise the current truth of this, but I feel a deep wave of sadness as I remember that the computer to have in the 90s if you wanted to customise evvvvvvery little thing was a Mac. A ton of custom aspects were available right in the base system, plus of course a seemingly infinite array of inits and cdevs to tweak things, and finally you could resort to ResEdit to modify anything by hand. Apple fell so far in the 2000s and especially the 2010s from that ideal.