As a professional graphic designer who spends my working life doing graphic design, I can confirm reducing it down to “contrast” is an amateur approach
This is all just just opinion dressed as absolutes. Whenever anyone engages in this nonsense I get bored very quickly. Both professionally and as an amateur. And when you use words such as forae my wanker alert starts blinking wildly!
I have plenty of opinions on how I like things to be done but I don't go online and express them as right or wrong. Often when asked I will express my reasons on why I do things the way I do only to have someone point out why they do it differently for reasons I never thought of. The OP probably makes some good points but I dislike the adversarial posture so much that I'm likely to disregard them!
Different design priorities result in different design choices. Low frequency (audio) electronics are pretty forgiving, so there's more room for discretion and fewer universally agreed upon best practices.