Like when you send a .7z instead of a .zip or .rar to a friend or a teacher because that's what your computer has installed and they're like "Oh No, not one of those, now I have to install 7Zip" even though the same program that opens .rar also opens .7z I feel like people are way more annoyed when they receive a .7z
Removed by mod
I'm on a relatively well known private tracker. It's just a kind of a tradition of some release groups to do this. I think it goes back to the times where this shit was shared through unstable FTP servers where you needed to restart the download of a file if the connection broke so they .rar it and split it into a dozen or so chunks. Nowadays it's almost certainly unnecessary but they still do it.
I'm seeing it less and less thankfully.
It was usually split into chunks because the upload websites only allowed files of certain sizes. Like 100MB or something.
Ah you're right, completely forgot about those. They were absolutely dreadful to use.