The K3 Visa was something that was created to be a complement to the K1 fiancé visa. It was created with the intent on the part of immigration to make the wait time for the spouse visa shorter so that a couple could apply for both a spouse visa and then they could also get in line for the K3 Visa. It used to be a faster option and whichever line was faster, then the couple could be together sooner.
Unfortunately, the K3 Visa is really something that’s no longer issued by immigration. It’s still a benefit for which you can appl but like so many wait lines, the K3 Visa wait line is longer than the spouse visa, defeating the purpose. Yes, you can still apply for it but the spouse visa is still the fastest option.