Most people won’t even try the potentially more healthy diets (compared to the standard junk diet) that the low-fat folks recommend either. Those diets also emphasize real foods, prepared with healthy fats (by which they mean olive oil), made from fresh ingredients, and elimination of sugars and limiting starches.
But doing all of that is difficult, or at least time-consuming and inconvenient, and people are out of the habit of regularly cooking and preparing ALL of their meals, or practicing conscious portion control when dining out.
So they will focus in on one part of any recommendation, and then whatever buzz-word sticks in their minds will start showing up on the labels of manufactured food products and they’ll buy that, thinking they are doing something right.
But eventually time pressures, convenience, and habit will override good intentions and they’ll be back to their old ways and nothing will change.
I’ve been doing this for 4 months and it has taken a lot of commitment for me to stick to it, and I spend a lot more time than I did before dealing with food - grocery shopping, prepping, cooking, eating, cleaning the kitchen, learning recipes, improving cooking skills. MAN was it ever easier to just do drive through on the way to work, or grab something in a nice little package from a vending machine.
People will not, en mass, switch over to healthy eating unless it is convenient, economical, and the foods eaten actually reduce hunger by natural satiety and don’t trigger additional hunger because of hyper-palatability.
So all of these competing diet trends are just competing for the very few who are actually willing to commit to a change (and are trying to pick the right path for themselves), or competing for the marketing mind-space to collect money from all of the people who are desperate for results but lack the mindset or ability to make the real changes required.