I understand her conclusion as "people study old philosophers, not to learn about their views, but to learn about their thinking techniques". In contrast, I would say that the primary reason for studying old philosophers first-hand is to properly understand philosophy.
(I wouldn't start by studying the old philosophers - I would start by reading modern summaries, especially those that focus on the actual philosophical problems. Study the old philosophers only if you want a full understanding).
You have to understand what philosophy is. It's studying the fundamental nature of reality and our thoughts about it. When you get down to fundamental issues, there are often a very small number of plausible answers, and much of philosophy is extrapolating the consequences of those answers. These issues are timeless and still relevant.
The pervasive modern belief is that philosophy is mostly meaningless word-games that can be dismissed, and science should be the basis of everything. But collecting more observations of reality does not help answer these questions. Furthermore, without knowledge of the implications of certain answers, you easily wind up advocating positions that don't actually hold up. (E.g., many people think neuroscience has disproved the existence of consciousness, when all it has proved is that consciousness is closely related to the brain).
Like Katja, I used to follow Lesswrong-style rationalism, but after studying different philosophies I concluded that Objectivism made the most sense. (Whatever you may have heard about Ayn Rand, I recommend evaluating her views for yourself). Leonard Peikoff gave an excellent and comprehensive course on the history of philosophy from an Objectivist POV: https://campus.aynrand.org/campus-courses/history-of-philoso...