Law terminology specifically can seem pretty archaic because there’s a high need for terms to be stable over time. In other fields and everyday speech terms can change over time. There’s contracts signed decades or even centuries ago that are still binding today. So it’s practical in a sense if the words within and those used to discuss legal dealings don’t change over time.

Off topic but:

[…] said Matthew Hindman, a professor at George Washington University who studies digital emails.

How do you study analog emails then? Print them out?