There are actually a couple of rather good points behind this statement, if perhaps not clearly expressed, and I say this as a regular, even religious, user of Anki. The first point is that there is significant overhead to (1) determining whether a given idea is worthy of memorization, (2) formulating the idea into a memorizable set of facts, and (3) entering those facts into your Anki deck. In my experience reviewing the facts is the cheap and easy part, whereas the initial steps are time-consuming and tiring, and the cost is entirely up-front.

The second point is that exposure to ideas often follows the pattern of spaced repetition naturally, because the idea is part of the zeitgeist. Arguably this is a superior way to learn many things for a number of reasons. For example, it avoids the problem of your mental model overfitting the identically repeating stimuli.