On a very very rare occasion I've had to use it for scene cracks as other apps didn't work. They use WinRAR to archive it so on those very rare occasions it's the only thing that unpacks it
The commenter implied that there's a tool which is better than WinRAR in everything and therefore there can't possibly be a reason to use WinRAR. Which application is it then?
As an example, RAR provides parity records which allows recovery of large amounts of compressed data in case of data corruption. 7zip can lose all its content if one bit is flipped.
RAR provides much more support for underlying file system support which makes it more suitable as an archival tool. Things like NTFS hard links, streams, ACLs, all three timestamps. 7zip doesn't support that.
WinRAR in general has way more niche features for advanced use cases, while 7zip focuses on the basics.
I bought a lifetime license literally more than 20 years ago to support the developer. I use 7Zip for most stuff but prefer WinRAR for split rar archive support.