It's less so a myth, and more so that the Western diet tends to eat so little fruit that even suggesting that you can eat too much would lead to people eating even less than they currently do, worsening outcomes.
> We have some local hatcheries, so at the time, we were getting significant runs back, and so they were willing to provide the salmon. Obviously, I don’t have enough students on board to go pick huckleberries in the amount that big grizzly bears or brown bears would want to eat. But we have an apple orchard right next door that is very — the apples are very, very similar in terms of being a lot of water, high carbohydrate and not too much else. We started doing studies where we would feed bears, if we’re talking about salmon, all the way from just maintaining their weight up to gaining prodigious amounts, and the same on apples. And then, so the next thing we did was feed both apples and salmon. And we let, in a lot of studies, we let the bears just determine what that mixture would be. And when they mixed them on a daily basis, then they gained more weight per unit of energy intake than either salmon alone or apples alone. And so there was an interaction effect, where by consuming both foods, it actually provided a better diet than either food alone. And that was what we were seeing in the wild bears. So the captive bears, given the choice, would do exactly what we were seeing in the wild bears.
https://www.ktoo.org/2022/10/13/bears-eat-far-more-berries-t...
> Conclusions: Current evidence suggests that whole, fresh fruit consumption is unlikely to contribute to excess energy intake and adiposity, but rather has little effect on these outcomes or constrains them modestly. Single-meal RCTs, RCTs lasting 3–24 weeks, and long-term observational studies are relatively consistent in supporting this conclusion. Whole, fresh fruit probably does not contribute to obesity and may have a place in the prevention and management of excess adiposity.
I shouldn't have said "does" but "can" would have been more appropriate.
"Eat whole fruits regularly and in moderation" is much better advice overall. Simple, to the point, and cuts out problematic ambiguities.