Those metrics imply that what images are being used is completely irrelevant. Either that's true, and we could all just use the same photo everywhere (I suggest the one of St. IGNUcious, Your Mileage May Obviously Not Vary - all hail the irrefutable and infallible 2.3x metrics!) or it could still be true that a "super generic stock photo at the beginning of an article" is, indeed, pointless.

I wonder if that is because of social media. In which case add the silly image to the metadata for embedding as a tweet, but keep it out of the post.

That number refers to actual images in blogs, not specifically stock photo thumbnail.

Perhaps I’m just an outlier; but every time I see a thumbnail that has nothing to do with the title, I scroll past it. It’s a negative for me.

Yes also due to shortening attention spans