No, not as simply as that. That's the basic idea of recommendation systems that were common in the 1990s. The algorithm requires a tremendous amount of dimensionality reduction to work at scale. In that simple description it would need a trillion weights to compare the preferences of a million users to a million other users. If you reduce it to some standard 100-1000ish dimensions of preference it becomes feasible, but at the low end only contains about as much information as your own choices about subscribed to or blocked communities (obviously it has a much lower barrier of entry).
There's another important aspect of learning that the simple description leaves out, which is exploration. It will quickly start showing you things you reliably like, but won't experiment with things it doesn't know you'd like or not to find out.