I can give you two reasons why someone might want to change it opten.
Many online vote/polling sections will usually drop a cookie on the visitor, when clicking submit or whatever is used to accept the vote that they have voted. One vote per device. It’s quick and easy.
That’s reason for using cookies.
The reason for NOT using cookies is that they are not immortal.
I tested a client site and I could vote every 12 seconds. Easy, and if I can do it, anyone can.
We set up a system that grabs the visitors MAC and records that MAC as having voted (done right after clicking vote). It’s hard as you know, to spoof a MAC, but even harder to remove that data from the sites encrypted database.
A bigger number of sites abuse our privacy by grabbing the MAC off the CPU, GPU, and APU in order to more accurately track our travels.
Easy-fix for that I use any of the stalker-blockers that block reading the addresses.
And for fingerprinting the CPU, GPU, and APU other browser plugs report a discombobulated version (smudge) of the actual Fprint would have been.
I’m sure that a lot has happened since back then, but maybe some will upgrade this.