I think @erlend_sh’s response to this concern is pretty spot-on:
Plus, more often than not you’re reading new stuff from the latest page. So first, you don’t get barraged with the extra character all the time anyway. And second, since you get well trained to see things as MM DD.
So seeing MM YYYY when you get to an old post is a good call-out that these post are different than what you’re used to seeing.