Some 1980s native advertising from Germany

I’m in Germany staying at my parents’ and have just been reminded of a type of native advertising we used to get in paperbacks, like this one.

From this sort of era.

You’d read about kayaking for a bit, and then all of a sudden, you’d come across some bonkers illustration that looks completely different from the others in the book.
The illustration would somehow relate to the topic of the book. In this case, paddling.

And on the next page, the copy would, with some considerable mental gymnastics and loads of metaphors involved (“keep your head above water”, “stay the course”, etc), bring the topic round to municipal bonds and where to buy them.
What I’m taking from this: Native advertising has always been clunky, even when it tried hard. (and didn’t take itself too seriously)

I don’t like the idea of being served an ad in a book I paid money for. And I doubt the ad made the book cheaper for readers to buy.
But 1) The targeting strategy seems solid: people interested in kayaking for pleasure, or even toying with the idea of buying a boat, probably have some disposable income, if only a moderate amount. It makes sense to suggest they invest some of it.
And 2) I love how hard the copy is working here. See the paragraph above (despite the clunk).
Even better (though not related to the ad): the positioning for this series of sport-related books: “Mehr Spaß am Sport mit Programmen von Profis und Kniffs von Könnern”.
Punch and alliteration go a long way.
I couldn’t find any information about the success of these ads, but they did run for a good 20 years, apparently. And I don’t know how they would have attributed ROI back then. But I’d love to find out how people felt about them. If you’ve got any insights, let me know. But it might take me a while to respond. I’m going kayaking.