It's not a question of being unable to co ordinate, simply that it's perfectly possible to put easier bosses in and ramp up the required effort over time, especially on normal modes.
Stone guards needs nerfing - or to not be the first boss of the first raid of the first tier of mop.
Theres no entry level raid again. It's LFR that is a new players entry to raiding according to some, which is going to be 14 tank and spanks that said new players get carried through by grumpy veteran raiders with zero interaction and then a huge step up to stone guard normal.
Poor design, end of story.