The stardates were never meant to make sense in TOS. IIRC, Roddenberry even said they were actually meant to be inconsistent, to reflect the each region of space uses its own dating system which the Enterprise adopts while in that region. This way here the writers don't actually have to keep track of the dates to make sure everything makes sense. Disco and SNW are merely going back to this original Roddenberrian intent, which which the other shows from TNG onwards disregarded when they actually tried to make the stardates make sense.
And holy shit, my spellchecker recognized a word I thought I was making up while writing this post, "Roddenberrian" but doesn't recognize stardate.