Back when we used consumed very little electricity, there wasn’t really a need for dedicated circuits. Even when the toaster blew the fuse when the kettle was plugged in at the same time to the same outlet it really was a matter of replacing the fuse and remembering to not do that again.
Now the demand for electricity in your home is more complicated. It seems everything depends on electricity (although most electric equipment consumes less energy than even 5 years ago)and you must have clean electricity for electronic equipment and separate electricity for critical loads.
Let’s talk about electronic equipment. Computers, entertainment equipment, smart fridges, stove, washers, dryers (gas or electric), furnaces, heat recovery ventilation systems, freezers, microwaves and even coffee makers all have micro-computer control. If the electronics are continuously exposed to changes in the flow of power caused by larger appliances as they cycle on and off, it wears out the electronics prematurely. The answer is to separate the sensitive appliances from each other by putting them on their own circuits. Providing a dedicated circuit with surge protection to run your entertainment, communications or computer center is the key to longevity of this equipment and it costs a fraction of the replacement value. The absence of other equipment on the same circuit brings the surge/dip cycle to practically nil.
Now to critical loads. If you have critical equipment putting it on dedicated circuit is the smart solution for reliability. For example: If you rely on a private water system to supply your home you want the heat cable protecting it from freezing in the winter to be absolutely reliable. Don’t plug it into the same circuit that runs the block heater for your truck. The breaker will trip and you’ll have two pieces of equipment lying useless. Another bad example seen is that of basement chest freezers and sump pumps: Don’t plug the freezer and/or the basement fridge in the sump pump outlet. Choose a different circuit. Sooner or later you will end up with spoiled food floating in a flooded basement.
The assessment, installation and maintenance of dedicated outlets is a hallmark of a well-maintained electrical system and is a fraction of the cost and inconvenience of even one of these disasters.