Taken from Wowhead:
Finally, our Raid Finder item. With a base Item Level of 835, it needs to upgrade 12 times to make it all the way to 895. Long story short, that's a 1 in 4096 chance of being 880. Let's say you get 2-3 items a week from fully clearing Raid Finder. You'd need to run Raid Finder every week for over 21 years in order to have a >50% chance of seeing a 895 item out of Emerald Nightmare LFR. By that time, we'll all be in item level 4000 gear as we play the latest Corgis Unleashed expansion on our VR decks (unlike the rest of this post, this part is entirely factual). But hey, you'll probably have that 895 Raid Finder item. Or you still might not. Still feel mandatory?
This was with made up numbers, and the chance is actually lower but it was written that way to make it easier to explain.
Everyone should read this:
http://www.wowhead.com/news=253854/t...stem-in-legion
How can people honestly go around and complain about this when the chances to even get a lfr item to max is so low is beyond me. Nothing wrong with the game, only players.