As someone who suffered from insomnia for most of his adult life, I honestly hate when people include "sleep well" in lifestyle choices. As it's something you can easily, or at all, control. On the plus side, diet specifically low carb diet finally cured it for me.
I get frustrated when people demand a special carve out for their situation in general advice. I mean, I guess they should have written:
Eat healthy (most of the time, unless you are in experiencing food scarcity, sorry), sleep well (unless you have insomnia, then try your best), rest (unless you have small children, then good luck), exercise (unless you have long COVID, there seems to be a trigger effect from exercise), manage stress (unless you are in a war-torn region, then I'm sending my prayers) .. and you should be fine (or your best you if fine isn't possible).
Sure I'm probably biased but I believe sleep quality is a little more difficult to control than the other points you listed. I can't even fathom consciously having bad sleep habits and not fixing them given how disrupting insomnia has been for me.
Honestly, my wife has insomnia and it is not only difficult to manage but it interacts with all the other issues: increases stress, makes eating healthy difficult (reduction of will power) and exercise is harder to recover from.
I'm sure it's frustrating to hear over and over again. But generalized advice doesn't and can't apply to everyone. Many people have extremely poor habits around sleep, and don't appreciate or dismiss the importance of it.
Maybe there's some underlying pathology in more cases than you will ever see acknowledged in traditional medical research (e.g. person is mildly addicted to being on a computer screen, or person has breathing problems that make it hard to sleep soundly). But that still doesn't make it bad advice on average and in general!
