The weaknesses are less obvious because the entire profession of economics exist mostly to made these weaknesses obscure with smoke and mirrors. The trouble with maximizing profit is that its success leads to a decline of purchasing power, which in the age of mass production, the system cannot afford. The question then becomes how to make capitalism leave enough crumbs on the table for the masses so that new capital formation will continue to be needed, which economists define as growth. The whole world is trapped with overcapacity and the people actually producing the stuff cannot afford to buy them, while the people reaping in all the profit do not need them. Its the all the books are safely back in the library syndrome, the dream or nightmare of the librarian, the equivalent of all the money safely back in the bank.
Production needs to be consumed.
Capitalism structurally conflicts with this simple truth. Instead of pay raises, workers in the Core are awarded with low priced imports while workers in the periphery are organized to produce under plantation conditions and at less than subsistent wages. Morality aside, this scheme structurally exacerbates the oversupply dilemma. Keynesianism is on target when it claims that high wages and benefits is the only long term salvation to any capitalistic system. It is utilitarianism, not moralism.