The System Is the Customer
Every time you choose a model like e.g. a business model canvas or a customer journey you are choosing which information is important to you and which information is not.
e.g. if you map a customer journey for a trip from home to work using public transport you are saying that how many buss drivers there are is not a part of your problem to solve, or that you don’t need to calculate in the scarcity of busses, cost of fuel or the city’s traffic or noise pollution regulations.