The electrical grid is wired in parallel. Why?
The benefit of having your home wired in parallel rather than in series is having a uniform voltage rather than a uniform current.
Because your home is wired in parallel, manufacturers of electrical products can set a specific resistance and know the expected current because of ohm's law V=IR, rearranged to I=V/R.
The danger of having everything wired in parallel is that increasing the amount of resistors in the circuit decreases the equivalent resistance of the entire circuit. This can lead to a dangerous amount of current travelling though the wires in your house. However, there are safeguards preventing a dangerous amount of current from damaging the products in your home.
The circuit breaker exists as the weakest part of the circuit that is your home. This ensures that, in the case of a dangerous amount of current, the circuit breaker flips first, so any products plugged into your outlets are kept safe.
Wiring in parallel makes developing electrical consumer products easy and protecting against the dangers of parallel circuits is done by the circuit breaker.