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 Conventions :
Katsucon (Washington, DC) - Megacon (FL) - Colossalcon (OH) - Anime Weekend Atlanta (GA)
Upcoming costumes : Princess Garnet (coronation gown) from FFIX, Edea Lee (various costmes) from Bravely Default, and more!