Framework knowledge evaporates. Low-level knowledge compounds.

Learning low-level programming concepts through hands-on experience leads to deeper understanding and retention, whereas relying on framework knowledge can result in shallow understanding that resets with each new project. Building a TCP echo server from scratch helped the author understand the underlying mechanisms of async programming. This approach can be applied to other complex topics like idempotency, back-pressure, and state machines. It's a trade-off between upfront cost and long-term benefits.