It’s so people can’t commit fraud mostly. There’s an epidemic of people buying something from a place like Amazon and then 2 years later buying it again and returning it but sending the old one back instead.
This allows tracking of that. Otherwise the company loses money and has no recourse. I get it from that perspective. Even some phone cases have the same thing. Apple cases. Pikata cases. Many things and it is for this reason mostly.
Not so they can track theft or hopefully track you.
I had a v1 and it has a unique identifier. A serial number. I saw it myself. I had to give it to peak design for a warranty
https://peakdesign.zendesk.com/hc/en-us/articles/115004982006-Finding-Your-Serial-Number-or-QC-Number#EDBV1SN
Also, when I bought my newer one from REI they didn’t get my information at all. Maybe it’s different for the travel line I don’t now. But I’ve never had to give my information during purchase unless it’s online