Labeled Socks are Now a Thing in Boise

I made a quick trip to Seattle this weekend to celebrate my mom's birthday, and in my haste to pack, forgot my socks.  I picked up these new ones, and noticed a strange feature.

My new Under Armour socks are labeled left and right.  Is that a new thing?  Is it in any way necessary?

I made quick trip to Fred Meyer near my parents' house and found a three-pack of socks on sale.  I made my purchase, headed back to the house, and when I opened them up, found they had a label for left and right.

As I looked closer, it did appear they had some design elements that would be applicable to specific feet, but when did this become a thing?  Is there actual science or purpose to the designated feet, or is this just a marketing ploy?

It's the first time in my life I've ever had socks that were assigned to specific feet, and it was maybe the most humorous moment of the trip.

A couple other pics from our celebration for my mom as we played with phone filters and watched the Seattle Mariners (lose and) retire the jersey of Edgar Martinez.