All economic models must involve simplifications because:

a$.$ they always try to duplicate all possible information and cover all possible variables that might influence decision making.

b$.$ we must rely on value judgments and ignore reality.

c$.$ economists would be unable to command high salaries if their models were so simple that anyone could understand them.

d$.$ human behavior is very erratic and unpredictable.

e$.$ reality is too complex to understand in its entirety, so we must reduce the complexity to a level that we can understand.