If you're using your Internet connection for other things at the same time, for example in an office environment where others are using the Internet to do their jobs, then having an FTP transfer use up all the available Internet connection bandwidth means that the Internet will slow to a crawl for others, making it almost unusable. Yummy FTP is particularly good at using up all the bandwidth, which is normally a good thing

, but a bandwidth throttle on Yummy FTP would control the amount of bandwidth that could be used for FTP transfers, thus eliminating the problem.