No sooner do I put up a post about copy editors' preoccupation with dog-whistle distinctions than someone turns up commenting on a post from 2011 on the newspaper last/past crotchet:

Everywhere I've been the distinction has been made. In most cases context makes it clear. The question for me is whether there should be a distinction between "last year" and "during the last year." One refers to a specific time, the other a concluded period in the past. Why not end all argument and keep the clarity of "during the past year?""

This is how it goes: Even after the concession that the usage is almost always clear in context, and insistence on a gossamer distinction. 

The hard-shell attitude on the issue came from a commenter even more pompous than I who styled himself THE GRAMMARIST:

"Last" and "past" are separate words with distinct differences in nuance and usage, and they are not interchangeable. When applied to describe a period of time originating in the past and continuing to the present (to the very time of writing), the correct word is "past." 

He goes on beyond that, at some length. My response:

Grammarist, you have the right to remain silent. You have the right to consult the Oxford English Dictionary. If you cannot afford an Oxford English Dictionary, one will be shown to you.

The OED cites this sense of "last": "Occurring or presenting itself next before a point of time expressed or implied in the sentence; the present time, or next before; most recent, latest."

The citations go back to 1377, in Langland's "Piers Plowman." Whether you approve of it or not, it has been a common usage in English for more than six centuries. 

It may strike you as significant that this supposed distinction is not addressed in Merriam-Webster's Dictionary of English Usage, Garner's Modern American Usage, Theodore Bernstein's Careful Writer, and John Bremner's Words on Words. In fact, the Associated Press Stylebook says merely, "Avoid the use of last as a synonym for latest if it might imply finality." That is, since I appear to have to spell it out, if last is clear in context, leave it the hell alone, even in AP Style. 

What is the reader supposed to be thinking if we use last in the sense of "most recent"? That we are in the End Times? That if we say something occurred "over the last year" rather than "over the past year" the reader will think that the Parousia caught us all unawares and time has stopped?

Since this supposed "rule" isn't even in the AP Stylebook, I would include it, if I were feeling Fowlerish, under the heading False Extension. I suspect that it has risen by extending the last/latest distinction, which does require a little attention. A writer's last book could be his latest or his final production. 

I appeal to you, colleagues, to put your time to better use. [Be advised: Another rhetorical question pending.] You have gone through a text, changing last to past, over to more than, since to because in sentences that are perfectly clear to any reader who has not been subjected to j-school language superstitions, and you're going to call that editing? You're better than that.