It's definitely fair for Blizzard to expect people that want to down a raid in normal to know each and every ability of their class. All it takes is minimal research and reading. After that you research the optimal rotation for your class and you're good to go. Addons help performance as well.
If a player doesn't want to put any research into their class and strive to become better, then they certainly don't belong in normal mode and are better suited for flex/LFR.
We've all been there. I remember back in cata when I started playing my Paladin, my numbers where abysmal because I refused to use Inquisition as I thought losing 1 Templars Verdict was too much. I was holding my group down and prevented them from getting bosses down so I stepped out. After a few hours of research I was the top DPS when I returned.