Why did apple have a 30-pin dock connector if USB can do everything?
https://www.reddit.com/r/apple/comments/yxrfu/comment/c5zw18d/
Why does Apple have a 30 pin connector anyway?

USB is a stack of protocols which is over complicated. Many USB implementations are riddled with bugs and people are used to just "disconnect and...

reddit
@SwiftOnSecurity Back when I worked with [a certain big printer vendor], prototype printer boards' USB would kernel panic my Mac. I finally had to use a sacrificial Linux box to test USB on early run proto printer boards.