USB sticks can fulfill part of the "2" in the 3-2-1 rule.

https://en.wikipedia.org/wiki/Backup#3-2-1_Backup_Rule

Not sure how i can collaboratively edit documents thanks to a USB stick.

I thought the same once, but apparently some of my friends literally do not own a PC. Only tablets or phones, no USB-A in the house except maybe in TV. Oh well, time for USB-C pendrives.

Surely you jest. I love USB sticks. But they are not a proper alternative to cloud storage. For example, how do I do share select files/folders with select people, in other countries?

Copy selected files to another pendrive. Use postal service to ship pendrive to other person. We used to call that sneakernet :D

But yeah there's a reason people don't do this anymore

Until you lose it, break it, damage it accidentally (via high humidity, high heat, etc). Arguably, if you run twake on some VPS, you have additional layers of redundancy by default.