This is a good move but several years too late. Google has already squandered it's lead in shopping when they replaced an excellent shopping search engine with a crippled advertising board that neither shows the cheapest prices nor a wide variety of products to buy. This has been compounded by introducing absolutely no substantitive improvements to the product over the past few years. Meanwhile, because nobody used t…
Nobody will remember it, but in eBay’s early days of success, Amazon spent a nontrivial amount of engineering effort into building an auction style marketplace. They actually built something that was better than eBay’s model by many accounts. Nobody cared and it was shut down, because Amazon is not where people go to sell things at auction. Just like google search is not where people go to do their shopping.
From the outside, it seems like Amazon doesn’t spend much time worrying about what Google and Facebook are doing. Not sure if that’s changed recently (Alexa, certain AWS products, Amazon original series).
In general, as companies balloon in size, it’s very hard to draw ROI out of the core product, and these companies tend to bloom into conglomerates (like amazon is, arguably). The biggest mistake you can make, IMO, is when you sacrifice the UX of your core product to benefit these “subsidiaries”, like google has done with shopping infecting search, as others have alluded to.