Why must we BALANCE chemical equations?
If you were a banker or an accountant, what is the importance of balancing your accounts?
In the banking and finance industries, there is a saying,
What works in the banking industry, also works on a much larger scale in chemistry. In every chemical reaction, mass is CONSERVED. FOR even the simplest reaction, if you have 1 g of reactants (from all sources), at most you going to get 1 g of product. In practice, you are not even going to get that. Losses invariably occur on handling.
The principle of conservation of mass, underlies reaction stoichiometry, which is a very fancy way of saying,
This is why I suppose teachers place so much emphasis on balancing chemical equations. If the equation is not balanced, you know that it is unrealistic, and chemically unsound.