Do people really still use WinRar? I thought that was a relic of the old internet.

WinRAR is simply obsoleted by 7zip. Or does everything WinRAR does and more. In my case, I particularly use their context menu shortcut for checking sha256 file hash

They can all serve the same purpose. The advantages of 7zip are the following:

1. It is totally free (as both in free beer and free speach)
2. The 7z compression format is superior to rar because it can compress either more or faster (not both though)
3. The rar format is proprietary. You are free to decompress but not to compress. In a business setting, you could theoretically get in trouble if you don't have a license. In some countries, e.g. USA, even outside a business setting. But if you have been using winrar forever, I can't see you changing your ways anytime soon! :)

You don't have to pay for the license /s