How do ionic equations work?
Well they conserve both MASS and CHARGE.
Financial transactions conserve cash: the credit made to an account corresponds to a debit from another account, or a cash item. If credits and debits do not tally, are not conserved, someone will complain.
Chemical equations, to be valid, must equally conserve both mass, and charge. If I have 10 g of reactant, from all sources, the most I can get is 10 g of product. In practice I am not even going to get that. Why not?
Chemical reactions must also conserve charge. If I start with neutral reactants, I must necessarily get neutral products. This is especially true for redox reactions, where we invoke electrons, negatively charge particles, as virtual products and reactants. To balance the reactant negative charges, there must be an equal aggregate charge for the products.