Gold-plated connectors. Directional speaker cables. £10,000 volume knobs. Better quality Ethernet cables for streaming audio. The world of technology is full of woo. When you're not well-versed in the basic knowledge of electronics it can be hard to know whether the advertisements or information you're seeing is legitimate or rational.
Many manufacturers have made money out of selling what is little more than snake oil. There are entire industries surrounding the promotion of such products, and you'll always find someone who bought something and can "really hear the difference in the audio output". When challenged on these claims some manufacturers will hand out various pieces of poor quality scientific analysis that don't always stand up to scrutiny.