It’s been said that a typical automobile today has more electronics on board than you would have found on a commercial airliner just a decade or so ago.
It would seem that series circuits are all we need to make our electrical systems do the things we need them to do. Not everything can be accomplished with series circuits alone.
The classical definition of a tool would be something like a hammer or a screwdriver; a tool that lets you do a job that you wouldn’t be able to do as well with your bare hands.