The hoax I wish would get around is that it is really good to smoke is dandelion roots. I love to imagine groups of teenagers running around at night digging out dandelions from random people's (especially mine) yards.
Most (but not all) things growing in your lawn you can eat though, if the area is free from toxins. The reason we have invasive species is because they came from somewhere else, and usually the reason they came from somewhere else is because they were what people ate before we discovered/invented better crops. Or at least this is true in New England and the mid-Atlantic regions, I can't speak for everywhere else.
And like gin: seems to get you quite drunk.
Everything came from " somewhere else" if you take the long view.
... wait, what? To think I've been avoiding them my whole life!
Dandelion greens are fairly nutritionally dense. They are high in vitamins and minerals, good for bones, blood and liver.
The vast majority of people who might have access to—or want to eat—dandelion are not malnourished and do not have vitamin deficiencies, and so adding dandelion to their diet will have zero net effect on their health. Swapping some vegetable out for dandelion will have zero net effect on their health. Replacing one doughnut with one portion of dandelion will have zero net effect on their health when compared to swapping out that doughnut for any other reasonable vegetable.
Individual foods are, generally speaking, neither healthy nor unhealthy. Diets are healthy or unhealthy.
It is funny the ideas that become popular, isn't it.
Consider also fresh food deserts that exist in many cities. https://en.wikipedia.org/wiki/Food_desert
Dandelions are widely available in most cities and very easy to grow, guerrilla gardening style. https://en.wikipedia.org/wiki/Guerrilla_gardening
From what I've read, they're actually beneficial for lawns as their long roots draw up nutrients from deep in the soil. Yet we pull them out and spray herbicides to kill them! I don't remember ever seeing brown patches caused by dandelions.