They are doing that for the Memory Leak issue on the S6 variants. I have 2 devices (Edge in my case) just configure you Google Account and the device uses 86% of the 3GB of RAM available. Other issues are battery and Wi-Fi stability. So they need to do that or sales for the S6 versions wil crash hardly.
Anyone that wants the Smart Switch PC app for Reflashing factory ROM, backup and restore, here is the link. Is from Samsung UK since was not found on the USA website.
SAMSUNG's Digital World