It matters a lot if you try to sort on that column

We're talking about how it's displayed on the frontend, not how it's stored on the backend

One persons front end is another persons back end.

Especially if you're a proctologist.

We use YYYY-MM-DD HH:mm:as on the frontend because it sorts lexicographically, which is useful for interactive tables.

You can use data attributes for that

There’s no need to have the sort value and the display value to be the same to allow sorting.

I think irrational’s point is that it’s trivial for any viewer, no matter the locality, to identify the date if there is no longer any ambiguity between date and month.

If you're not formatting a numerical date in the user's preferred date format then you're probably not localizing the month name to the user's language either.

How would 2012 ноябрь 12 feel to you?

Fine if I set Russian as my langague. I presume Youtube does localization.

So it could also take the preferred datetime format from the locale.