Yes, it is for spam prevention. Thankfully it never seemed to be as much a problem on the marketplace than on the forums, but the rule is there regardless.
2014 - Upcoming Conventions :
Holiday Matsuri (FL)
Upcoming costumes : Suzie Q from JoJo's Bizarre Adventure, Edea Lee (various versions) from Bravely Default, Robotnik (genderbend) from Sonic, and more!