Throttling enables you to disable input from an stream for a certain period of time, after first event. Example: You might want to call a submit button once - even after multiple clicks by a user. Or you might only want to call an api once after several keystrokes by user - as is case with "type as you search". Limiting API call on every user interaction saves you server side resources and also enhance user experience.
You can either disable the button or field from taking in more user inputs. But that's not elegant.