Yep, I’ve heard it.
And yep, I do let dandelions grow in my yard (although not my beds where I am giddy with victory when I get the whole root).
You see, the dandelion is one of the earliest sources of nectar for bees in early spring. Bees that over-winter use stores to get through the season. A longer-than-normal winter, like the one we're having this year, can mean bees are especially hungry when spring temperatures arrive. Having ample nectar in early spring is crucial for these pollinators to be healthy and maintain their numbers.
A perfectly manicured lawn of 100% Kentucky Blue might look lovely, but it is a nectar desert. Clover and dandelions feed a diverse host of pollinators.
Some folks don’t want dandelions, and I understand. If that’s the case, I’d point you to primrose, creeping phlox, anemone and pulmonaria as options in your garden so bees have a healthy meal waiting in early spring.
Or be a little bit of a lazy gardener and let a few dandelions grow.