The first manufactured patches I recall entering the hobby came from Upper Deck in the 2004 Sweet Spot Classic release. I didn't crack much if any of that product but I do remember seeing some boxes broken at my LCS. The "patch" card as it was called was usually the last card in the pack/box and featured a wide variety of famous players. There were also a number of different patches for many of the players in the set.
Here is a Christy Mathewson I picked up recently celebrating the 1911 World Series. Somewhat of an odd choice as the Giants lost that Series to the Philadelphia A's 4-2 with Mathewson going 1-2 in 3 starts (there was a 6 day rain delay in the middle).
Each player has several different patches produces in different print runs. I have 8 different versions of these cards in my Willie McCovey collection (print runs of 10, 25, 50, 125, 150, 200, 230 & 300). There is a version out of 75 listed in Beckett that I have never seen before, I suspect it doesn't exist.
As I recall, I liked these cards when I first saw them. They were new to the hobby, showed some creativity and allowed for some retired players to be more prevalent in the hobby. Once Topps got on the bandwagon and started calling manurelics "hits" in their Jumbo boxes, I started to change my attitude about them and got to the point where I almost despised them. I don't know if I am softening up as I get older but my attitude is flipping again and I am starting to like some of the releases.
Take for instance this 2015 Topps Series 2 First Home Run manurelic of the Kung Fu Panda:
These manurelics were inserted in retail blasters at 1/blaster, kind of an extra added bonus when you bought a blaster. I actually made the decision to buy a couple blasters this year in part to get one of these cards. I unfortunately didn't pull a Giant but got this one on Sportlots at a very reasonable price. These are very thick and heavy, the medallion in the middle is made of some sort of metal. The silver foil lettering doesn't come through that great in the scan but the card in person looks really nice.
As the oldest and newest manurelics in my collection, these cards represent what I like about this relatively new part of the hobby. There are still a few in-between that were ill conceived but hopefully moving forward we will continue to see nice cards with solid designs.