Brigitte says it's really weird to talk in third person

Through all my eavesdropping at playgrounds and stores and anywhere else Matthew and I run into other moms and kids, I've noticed something that both perplexes and inexplicably annoys me.

Wait, let Brigitte Mommy start over: Through all her eavesdropping at playgrounds and stores and anywhere else Matthew and Mommy run into other moms and kids, Mommy has noticed something that both perplexes and inexplicably annoys her.

Yeesh. Even in writing it's weird.

I've noticed that a lot of moms refer to themselves in third person when talking to their kids. A few examples:

"Joe, you know Mommy said we'd only be at the playground for a little while. It's time to go home."
"Get over here! Mommy told you no! Get off the picnic table!"
"Mommy's thirsty. Are you thirsty? Mommy's going to have a drink now."
"Mommy is busy. Please stop trying to bite her leg."

In each of these cases, the lady is clearly the mom of the kids. So... she's not some babysitter or friend or relative passing on instructions from the mom. Also, it strikes me every time that the person referring to herself in third person is always "mommy," not "mom" or "mama" or any other name by which moms are commonly called.

I just don't get it. People almost never use third person with their actual names, and when they do, other people find it odd and cause for mockery. I'm guessing these same ladies don't use third person with their husband or other acquaintances. So why do so many "mommies" do it?

Possible guesses:

• It sounds less authoritative to tell your kids "Mommy said" instead of "I said." It may make the mom feel less like she's bossing with that slight linguistic separation. (Though here, I'm the boss. I make the decisions. I'm in charge. I don't mind being bossy.) (Though here, Mommy's the boss. Mommy makes the decisions. Mommy's in charge. Mommy doesn't mind being bossy.)
• It's a holdover from when the kids were babies, e.g., "Mommy loves you so much!" *smooch, smooch, smooch baby face*, when the kid probably didn't yet know what to call that nice cuddly lady because the verbal skills hadn't developed yet.

That's all I've got. If you call yourself Mommy, and you call yourself Mommy TO your kids––why? Please solve this mystery for me!

Postscript: I am NOT a "mommy." I am definitely a "mom." And "mama" is only okay from Matthew, and only for probably another year.