In addition to what other people said, they allowed you to resume downloads. Even if you weren't on dial-up, sometimes downloads would just... pause. Like you'

In addition to what other people said, they allowed you to resume downloads. Even if you weren't on dial-up, sometimes downloads would just... pause. Like you'd get to 23% and just wouldn't get any more data from the server. With these programs you could make progress by restarting the download, and it would pick up largely where it left off.