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
I just use 7zip to make .zip if I think the person I'm sending it to won't know what a .7z is or how to unzip it.
I don't really see the point in using .rar or .7z in 90% of cases, makes very little difference in filesize compared to zip and anyone can open it without problems