Except it's dynamic unlike kludges on PC I think.
It doesn't waste any mem if it's not filled. It only uses the amount you've copied there.
It's very handy for unpacking, downloading files which you want to check before copying to disks and installing stuff etc. I use it all the time. It's fast and doesn't fragment the HD etc. You don't have to clean up mess.. it gets cleaned in reboot. And it's especially usefull with floppy only systems for file handling.
It's been fundamental part of Amiga always... also env variables reside there as well as T: assign for temporary files.
Then there's another interesting ram drive on Amiga, but you need to mount it separately. RAD: is disk residing in ram, but it survives the reboot (not power off (well maybe very quick))

It's also bootable. You could use it for quick boot device after first cold boot for example. Or have game disk unpacked there and boot from it.