You get a lot more views for a video on how to index a column in MySQL than for how to approach evaluating your needs and choose a suitable database. The latter would be outdated in a few years as new technologies emerge, while the former can be padded with enough fluff to show two adverts. So we end up with the content you know today, rather than what you'd really like to see. It's good to remember this and interact with those who do publish the latter content, plus it makes the algorithm feed you more content that's worth your time.