This is a tedious read that is mostly tangents from the headline. The question of “why copper?” is mostly about why not aluminum, silver, or gold. The article touches on aluminum but never bothers to answer why not silver/gold.

This article has no central thesis and is instead a mishmash of random facts about electricity flow through circuit boards (often weirdly specific at that). Don't read this article hoping to find an answer to the question posed in the headline

Money. Whether it's material cost, technological complexity or lower efficiency reasons, regardless, the reason is money.

You can tell it's going to be a quality site when the article begins with a selection of PHP warnings. One link gave me a 410 which was a surprise, until I realised it returns 410 instead of 404 for every missing page.

Please don't invest any time in these articles, the whole site is a bizarre AI generated marketing scam

Next: OpenAI buys all the copper mines.

Copper is not self sealing and thus destroys the electronics when breached by humidity? Makes it ideal.

Copper from electronics is recyclable, so I'm guessing we should see more recycling of electronics if there are any mining difficulties.

Copper will remain relevant for some things, but the very high-end will probably start using SiP-to-SiP fiber, and the low-end (consumer devices) have everything bunched so close together you have to ask "what trace?"

Because those lazy chemists have stopped finding new elements to use instead. /s