I think what you're describing is the best case, the world we should shoot for. But getting there for most people will take a generation of social change.
Meanwhile, most of us find ourselves in a shitty current situation where a healthy diet and a healthy level of activity feel weird and counterintuitive to us, and we have to trust reason and evidence to guide us to a healthy way of living, despite deeply engrained aversions, deeply engrained compulsions to engage in unhealthy behavior, and powerful external forces arrayed against us.
For people who are unhappy with where they're at and are looking for answers, telling them that there's an easy healthy way to live that caters to their current desires and aversions sends them on a lifelong journey of being disappointed by one set of false promises after another.
A more honest thing to tell them is that their life up to this point, their experiences, the norms they grew up with, the food ecology of the world around them, has warped their perceptions to the point that what is actually good for their body will feel unpleasant and psychologically unsettling. The unvarnished truth, which you might not want to dump on them right at the beginning, is that at times it will be fucking miserable. It's analogous to having a substance abuse disorder. Many, many times the only choice that feels comfortable and natural is the one that physically harms you, and resisting the compulsion to harm yourself feels awful. It can feel sad and scary not to eat every single donut in the break room, even if you've already had a generous healthy breakfast. At times like that, the "if it isn't easy, you're doing it wrong" message comes off like an unfeeling flex, like telling a depressed person to just snap out of it.
People may stigmatize difficult lifestyle changes as "restrictive" or "joyless" or "unrealistic," but it's not the fault of the lifestyle itself. It's the fault of what you've been fed your whole life and what the world continues to shove in your face and dangle in front of you every day. It doesn't kill joy not to eat cake. It kills joy to say no to cake eight times a day while a billion dollar industry wages war against your efforts to care for yourself by constantly reminding you of the momentary pleasure and relief you will feel if you give in, and people who care about you unwittingly act as their accomplices in all the spaces that are supposed to be safe for you.
> https://www.health.harvard.edu/staying-healthy/stop-counting...
People who work in public health are not giving advice to help you make a significant change in your life. They are giving advice that will do the most good for the most people, which realistically means moving the needle a tiny bit. That's what they're shooting for. They don't expect you to succeed at living a healthy life. They expect you to be overweight and to live a lifestyle that makes metabolic disease a likelihood, because the societal context is stacked against us. They've accepted that their power to help people currently struggling with their health is limited to changing a fraction of a percent here and there, and to achieve significant results we need to focus on changing the context for the next generation. Which we do need to do, but meanwhile, if you don't want to write yourself off as a victim of the times, don't let people tell you that easy is the only healthy way. You won't regret doing your best to take care of yourself, even if it's a struggle and you can't pretend it's easy like everyone tells you it's supposed to be.