I get that different products would be pretty siloed within their corporate structure, so I know that they weren't just going to use the YouTube code. However, why are products that are released well after plenty of other apps have forged a path so that the new app can research what works and doesn't work, what do people like/not like, and all of that type of basic information just so abysmally ignored so that this "new" thing is so inferior?

If you're not the first pioneering version of something, you better be doing everything the others are doing, but better. Otherwise, what's the point of your product?