If you supply a circuit from 2 breakers, how do you make sure they're always both off? Linking the handle only works if they're operated manually, if one trips it might not have enough force to trip the other with the free trip mechanism which is mandatory in Europe.
I don't believe in fusing circuits above the capacity of outlets anyway. In Continental European countries there's a simple rule: the smallest outlet on the circuit determines the fuse/breaker. So if an outlet is rated 16 amps, then it's no more than 16 amps, period. The UK tried avoiding this with the plug fuses without too much success. The US allow for 15amp outlets on 20amp circuits, posing a serious risk of overloading plug strips.
Let's face it - unless we're talking about large appliances like ranges, all-electric dryers or others (wired to dedicated circuits anyway), 16 amps at 230 or 240V are a lot of power. Why do you really need more than a few such circuits?
