I have no idea why you are so upset over someone protecting their legitimate rights.
As you pointed out, his equipment isn’t exactly cheap. How do you think he funds that? His day job will help, if he has one, but a lot of people who spends that kind of coin on hardware are also looking to generate income from their hobby if not doing it professionally. And that is what the watermarking is for.
If I was the editor of a legitimate publication and likes that picture and wants to use it in my publication, I now know who to contact to get a clean picture, part of the standard deal that goes with that is working out fees and acknowledgments.
We should just be grateful that we get to see the advertisement samples, and not unreasonably wanting to get other people’s work for free.
If you really want a clean version of that picture without water markings, you yourself can reach out to the photographer and ask to buy a copy. It probably won’t cost much for personal uses, but then you wouldn’t be allowed to post that clean version all over the internet, as then would be professional customers can just download that picture instead of having to pay the original photographer.