Why car engine block cannot be made using modular components?

Why car engine block cannot be made using modular components?
the block is a solid piece of metal, it has to be solid for strength. If you make it out of modular components then it will be more likely to break under the extreme heat and stress. Also, the individual pistons would cause a huge amount of vibration, which would ware down the engine faster, and most likely ruin the camshaft and other components.