I subscribe to a lot of channels, and they usually put out significantly more videos that I don’t want to watch than videos that I do. I’ll usually subscribe to a channel for a specific video in case they make more of that specific kind of video, but I won’t care about their other stuff.
For example, I subscribe to the Game Grumps channel, but I only want to watch them play games that I’ve also played, or that I at least know enough about to follow along with the gameplay without focusing all of my attention on it. If they’re playing a game I’ve never heard of - which they often do - then I don’t care to watch it.
The algorithm does a better job of showing me the videos I actually want to see than the subscription feed does because it takes into account which specific videos I’ve seen and skipped for each of my subscriptions.