I read this sentence and I don't understand what "punch line" means here:
Most people recognize this Amazon: Jeff Bezos's hyperproficient Borders-killer; one of the few dot-com initial public offerings that didn't end up a punch line; ......
I know the literal meaning of "punch line". So in this sentence, does it mean that most dot-com IPO companies failed like jokes, so they "end up a punch line"? This explanation sounds awkward to me. Could somebody please explain the usage of "punch line" here?