The step wise approach actually sounds very similar to something we did in the ED support communities I used to be a part of, except we called it 'stasis' (if it's not the same, let me know).
For us being in 'stasis' was a type of 'pre-recovery', it meant committing to try and maintain whatever weight we were at, to stop trying to actively lose weight, and to start work on challenging harmful ideas or behaviours. So 'stasis' for me, which I did for a year before going into full weight and nutrition restoration mode, meant maintaining my weight at my then BMI of around 14.5, refraining from actively trying to lose weight (not easy), and each day I would pick one aspect of my eating disorder to challenge: that could mean anything from deciding to put one extra slice of tomato on my half a sandwich for lunch, not completing all the steps of my entire weighing ritual, walking into a grocery store and just buying a packaged food item without having to sit on the floor of the shop and then pull the entire stock level off the shelf in order to find the one that 'felt right', or just spending a day 'talking back' to my disordered thoughts & trying to challenge certain ideas I had objectively. To outsiders it might not have looked like I was making any progress at all, still emaciated and engaging in disordered behaviours after all, but that step by step, day by day approach was a huge deal for me and what eventually helped me accept the switch into attempting full recovery.
As for the 'step by step' or 'stasis' mode of recovery being useful across all age groups, I would agree with that. I've seen young teens successfully use this method, and I've also seen women and men in their 40s or older successfully use the same method. When I said 'treat patients as individuals' I was talking more from the theories of causation in therapy point of view and what then stems from that. I have seen therapists and psychiatrists who were so rigidly hung up in their 'one true theory' approach that it impacted their ability to engage in meaningful therapy with their patient. Like if I have anorexia nervosa and I go to you for therapy or support, and your pet theory is that I have anorexia nervosa because I'm scared of growing up, and I tell you "Nope, that doesn't match me at all, not even a tiny bit", and you continue to insist on approaching therapy/support from a point of view that I've just adamantly negated, then that's gonna be an issue going forward.