Well, guess what, the Richelieu also had no rear (main gun) turrets, and she packs more of a punch then the Nelsons (in terms of shell weight per min able to deliever to opponent). Below is my calculations:
equation: # of guns * shell weight (lbs) * 60s / fire cycle (s)
Richelieu: 8 * 1949 * 60 / 32 = 29235 lbs
Nelson: 9 x 2048 * 60 / 38 = 29103 lbs
Yeh, the Richelieu won despite the Nelson has one more gun and uses a bigger calibre gun (16" > 15"), though not by much I have to admit.
Anyways the Nelson would have to fire a full broadside to acheive her max firepower, while the Richelieu need not. Don't argue with me that half of Richelieu's main battery can be knocked out with one lucky shot since the Richelieu's guns also have a longer range compared to the Nelson (41700m to 36375m)