There is a problem with self closers if they are wrongly set, which, usually, they are. 20 newton (gram) opening strength is the theoretical maximum, but if it means a disabled person or other user of the building would be trapped in a fire, there isn't any need to have any particular number (weight of pull spring). There are two parts of the closer, the initial/final and the main sweep. There are also two parts of the control, the speed and the force.
In every case, doors and closers are installed by whichever bloke has the screwdriver, and he rarely " has the body of a weak and feeble woman" (to quote Elizabeth 1) ! He will push vaguely at the door, confirm to himself that he can open it, and go. Nobody checks, not on snagging of newbuild, not on box ticking of building regs. people (usually blokes).
The theory behind them is fine. If people simply run out of a building leaving the door open, the fire spreads faster upstairs. My question might be, how often does that happen, including when people know there are other people upstairs ? And how much back, wrist, arm, finger and leg injury and general human misery is caused, thousands of times an hour, by the burden carrier hating, woman hating, cripple hating, child hating, old people hating closers?