Why do many web.UI need flow control, such as verify, wait

Does anyone know why a lot of web.UI needs flow control, such as verify, wait for…, case can be better implemented, I am currently imitating others’ writing stage, I don’t understand the reason very well, and I often don’t know it. inside

Have you read this?

Do you want to say you do not need any FailureHandling at all?

Yes, just read it right after I published this post