I don't know much about the device you describe, but fastening papers with something like this is probably way better than staples if the goal is long-term storage. Staples and other metal fasteners are pretty destructive. The National Archives offers guidance for fastened document preservation, for example, here: https://www.archives.gov/preservation/holdings-maintenance/f.... Staples can add a lot of unneeded bulk to records, too.

There still is. We have a couple of these in my house. It's not as effective as a metal stapler, but it works well enough for things that we don't need permanently connected (plus it's much safer for my 6-year-old kids to use).

Apparently these are called a "paper clinch".

There are crimp-type devices, and there are ones that cut a slot and tab. The slot and tab devices were patented in 1910. The main one was the "Bump Paper Fastener", which shows up on eBay now and then. So that's automatic letter-locking.

[1] https://pdfpiw.uspto.gov/.piw?docid=01065904&