It draws attention to a problem that a lot of people have created for themselves by not reading the documentation (or not recalling it if they read it). I guess the author could have just linked the documentation but then they couldn't have added the additional context of the github search demonstrating how common it is.
I must have looked through the docs for create_task a dozen times while trying to figure out how async/await works in Python but still managed to overlook this part.
The author doesn't go into much detail on that point: this warning should be present in documentation of many Python libraries that use create_task and return the result to the user unless that library stores those tasks in a collection as is recommended -- at which point the library author had better roll their own garbage collection!