But what if I want a faster horse?

For any given thing or category of thing, a tiny minority of the human population will be enthusiasts of that thing, but those enthusiasts will have an outsize effect in determining everyone else's taste for that thing. For example, very few people have any real interest in driving a car at 200 MPH, but Ferraris, Lamborghinis and Porsches are widely understood as desirable cars, because the people who are into cars like those marques.

If you're designing a consumer-oriented web service like Netflix or Spotify or Instagram, you will probably add in some user analytics service, and use the insights from that analysis to inform future development. However, that analysis will aggregate its results over all your users, and won't pick out the enthusiasts, who will shape discourse and public opinion about your service. Consequently, your results will be dominated by people who don't really have an opinion, and just take whatever they're given.

Think about web browsers. The first popular browser was Netscape Navigator; then, Internet Explorer came onto the scene. Mozilla Firefox clawed back a fair chunk of market share, and then Google Chrome came along and ate everyone's lunch. In all of these changes, most of the userbase didn't really care what browser they were using: the change was driven by enthusiasts recommending the latest and greatest to their less-technically-inclined friends and family.

So if you develop your product by following your analytics, you'll inevitably converge on something that just shoves content into the faces of an indiscriminating userbase, because that's what the median user of any given service wants. (This isn't to say that most people are tasteless blobs; I think everyone is a connoisseur of something, it's just that for any given individual, that something probably isn't your product.) But who knows - maybe that really is the most profitable way to run a tech business.

You’re way overestimating the effect an enthusiast has. Evangelism only goes far enough to introduce people to the thing. How often someone uses the thing depends entirely on its utility (usefulness).

As long as Netflix was successfully reading the author’s mind, they were satisfied with the experience. However, Netflix assumed that they want to keep watching the same content, oblivious to the author’s desire to discover something entirely new. Netflix failed to meet the expectations of those seeking something entirely different.

I can understand why Netflix made this change. They’ve replaced many shows with their own in-house productions. By doing so, they prevent users from searching for specific shows and then realizing that Netflix doesn’t have them. If this happens frequently, they risk losing customers.

On the other hand, Spotify doesn’t face this issue. Therefore, I’m puzzled by why they’ve made it more challenging to explore content by categories. (Disclaimer: I don’t use Spotify, so my experience is based solely on author’s observations.)