I can see that, but I disagree that it's enough of an explanation. The blog specifically gives an example of the Earth's angular velocity changing with the melt

I can see that, but I disagree that it's enough of an explanation. The blog specifically gives an example of the Earth's angular velocity changing with the melting of ice caps. They even threw in a cute animation of an ice skater to explain it. Last I checked, we're in the midsts of global climate change which is rapidly melting our ice and raising sea levels. I'm supposed to take Meta's word that we'll never need another leap second then? Why is that the case? Instinctually it makes sense to me to have a clock that follows the Earth's rotation. Why does Meta believe this is no longer the case? The only justification I saw was "it's hard" followed by their explanation of how they've solved it already. So what is the problem that's being solved by not counting leap seconds?