There’s at least one distinction I didn’t see in the article. If a throbber is advanced by signals of progress or at least action, then it’s not useless and is

There’s at least one distinction I didn’t see in the article. If a throbber is advanced by signals of progress or at least action, then it’s not useless and is arguably better than a progress bar that moves with unpredictable and uneven speed. If a throbber is an animated gif displayed until something makes it go away, then it’s useless.