carriers for whatever reason are responsible for the final updates for everyone, so once the final build is released its kinda out of samsung hands.
It should be revised to how apple does updates. even with 3 years of support, it would make the experience better. Less adware from the carriers too.
Samsung must have an agreement with the carriers that they get the updates first. Why else would unlocked phones be last to get the updates. Just saying. I am currently ok with the latest beta, but it would be nice to get the stable update.