It's hard to emphasise just how important the newspaper classifieds were. If the telegraph was the nineteenth century Internet then the morning newspaper was the eBay of its day.
The paper acted as conduit for folk to exchange products and services, to find love or find a lost puppy.
There's a little bit of those other sections that finds itself again in the classifieds. I've seen magazines that are principally ads for cars for sale. It doesn't seem to matter that this is going to go out of utility faster than fashion and current affairs; once the vehicle's sold, there's no more to be said.
Perhaps magazines have an expectation of durability beyond that of the newsletter and so we don't expect to find ones designed for obsolescence. Trade journals and academic journals don't particularly hope for this since they want return for their investment and neither a model of commerce nor a theoretical model are of much use if they are replaced before they can meet that benchmark.