Its a combination of them. The promoted listings (and many consumers considering purchase price in exclusion to lifecycle cost) cost sales of superior products, eventually making those products uneconomical to produce. No matter how much better they are, and how well promoted they are, you will have a hard time selling a lot of $500 keyboards in a world where $10 functional ones exist and $100 decent ones exist.
I actually had a miserable time yesterday; my mother decided that her Intel MacBookPro (or rather my late fathers) was getting slow; it must have been 7 or 8 years old I think, and had me walk her through buying a new computer which ended up being an iMac. I learned this was a mistake; I should have steered her towards another MBP.
Anyway, the relevant thing was I was trying to explain to her several keypoints: 1) since she has recently been diagnosed with carpel tunnel, she probably doesn't want a keyboard angled the way my dad's laptop's keyboard was angled (up about 35°), 2) If she is going to use a mouse it needs to have wrist support for the mouse pad, and 3) LOOK AT THE PRODUCT! I don't care if the title says this mousepad has wrist support; the images of it clearly show it does not! Either the picture is bullshit, or the title of the listing is; DO NOT BUY IT!
Likewise, she was considering a 'ergonomic' mouse of the type you hold... oh boy I can't describe it, here:
View attachment 400072
Anyway, she wants that mouse located like a trackpad is on a laptop, so just in front of the spacebar. I couldn't explain 1) a description of ergonomic means that somebody either finds that product ergonomic for them or thought they could sell a product like this with the description of ergonomic; it does not mean its actually better for everyone, and 2) It is inherently impossible to leave a mouse of that shape in front of your keyboard and type on the keyboard.
I think a lot of products are sold because people trust descriptions written by people trying to sell products! Why bother making it good if consumers are that stupid?