Why .rar Files are fine.
Like the person arguing against .rar files said, .rar files are standard. They're easy to use. Its a widely distributed format. It usually means the files come from 'The Scene' and that they're not amateur Cam's or Non-working cracks(For the most part, there are some not so good groups out there). In short, Its simple and it works.
The person arguing against .rar files listed a few reasons for why the existance of .rar's is harmful. The first of which is corrupted .rar files and it ruining the archive. This was dealt with by Rarlabs - the company that makes winrar - years ago. They added a little checkbox that when checked, allows you to keep all files extracted - even if they are corrupt.
Additionally, if it is corrupt, there's little chance of the download being unusable anyway. VLC can repair the index of a .avi file so it's still playable. Unless its the first or last .rar of a file, the CRACK dir should still be fine, and the program can still be installed normally unless a .rar is missing completely. If thats the case, then you just need to find better trackers and not complain about .rar's.
Also, even if Bittorrent has Hash checking for a file, it can lead to dozens to hundreds of megabytes being re-downloaded as well. While uTorrent and Azureus - both very good clients - ban peers for sending bad data after a certain number of hash fails, other popular clients don't do this - and even continue sending bad data after downloading it. The difference isn't kilobytes vs megabytes, but rather a varied amount vs a fixed amount. Oh, and good FTP clients can have .sfv checking scripted in so it automatically re-downloads a .rar as well.
When used with Bittorrent, .rar files aren't meant for compression. They're meant for getting the material around quickly. If each person downloads 1 .rar and then spreads that .rar around, it works in a similar way to Bittorrent downloading a piece and sharing it. Only this was used decades before Bittorrent came into existence. Not that FTP's or the scene works like that, but it's one potential use.
Or you could download half the file from one place then the other half from another if the tracker goes down. If it was one large file, then it's easier to edit and change the hash value of this so you'll have to re-download the entire file. Could waste up to gigabytes of bandwidth and space.
Space shouldn't be that big of an issue either. Modern computers have hundreds of gigabytes on average, and can easily be expanded into terabytes. Music doesn't come .rar'd up. There's no other reason to want an individual file to save space. If you just want to grab the crack?Then just get the entire thing from one place - it's easier and takes less effort.
Scene rules have nothing to do with Bittorrent. It's up to the uploader to decide if they want to extract the file or not. Usually they're concerned with getting the content out quickly. So it's easier and quicker to keep the .rar's in a folder and re-create the torrent with that folder then it is to wait for the files to extract and then recreate the torrent.
When used incorrectly, ANY compression is bad - whether it be .rar, or .daa, or .zip. If you have one big .rar - then the person uploading the torrent is an idiot. Don't single one thing out ignorantly because it's the most widely used one. At least .rar's have several programs that can extract it. Unlike .daa for example.
Plus, .rar files are easy to spread. After they're downloaded from FTP, they can be uploaded anywhere - IRC, FTP, Usenet, HTTP, or Bittorrent. For FTP, Usenet, and HTTP it's especially useful. Usenet's generally limited to ~50-100mb per file so having large files wont work. FTP and HTTP can cut randomly if your connection's unstable and not all servers support resuming. It's easier to re-download 5 of 15mb then re-download 600mb. Oh, and those HTTP sites like rapidshare people seem to like for warez boards, they're generally limited to smaller files with limited time as well.
As for credit? This has nothing to do with .rar's at all. Why even bring it up?