user-select is really useful. Not so much to protect text from being copied, but to provide a better user experience in little cases. Like let's say you have a row of little icons next to text. Nobody wants to select those icons, they want the text, so you could use user-select to make them unselectable.

But sad story, user-select isn't very reliable. It's not in the spec yet, which means there is no standard for browsers to follow. And as ever, the implimentations vary, as shown above. Just a small example of why specs are a good thing. They prevent situations like this.