Exactly. Honey has some water, but it’s more than 80% sugar.
Bacteria need water to grow and they absorb that water from the environment. Honey is so concentrated that bacteria can’t pump water from the honey into their cells. Or they can, but the water just osmotically diffuses back out faster than they can pump it in, and they dehydrate and become inactive.
You have to mix the honey with a lot of water before you create an environment that bacteria or yeast can grow. So to make mead you wash the honeycomb with water and then ferment the honey and water mixture.