That too, I guess. I just personally don't really mind it either way — a screencap from the 80s' Transformers cartoon with Optimus Prime in its truck form before an article about different implementation strategies of a "switch" construct? Sure, why not. And I bet that picture wouldn't trigger the same response in the original commenter.

Some blogs end up having interesting (not the right word, but I can't think of a proper one) sequences of leading pictures for their series of related posts, so that's an additional bonus for a reader, as a kind of second narrative/story, perhaps completely unrelated to the first one.