Why do language enthusiasts aged 25-45 who enjoy learning word origins and historical connections struggle with the letter "d"?

https://idiominsider.com/from-knucklebones-to-algorithms-the-evolution-of-risk-language/

Have you ever loved tracing a word back through Old English, Latin, or Proto-Indo-European, only to stumble when a simple "d" behaves strangely? Why is the "d" in Wednesday mostly invisible when we speak it, while the "d" in handled is very much