Why do cells not continue to grow as large as the organisms

Cells need to be physically functional and adept to its function in order to survive, growing larger would disrupt its volume and density. This would create a homeostatic imbalance.

They evolved to be small in order to survive: being efficient and functional in its processes and activities.

Cells are the fundamental unit of life, grouped through a series of organization. As basic histology explains the primal hierarchy between each organized organism has basic unit called cells. Cells when grouped form tissues, when group of tissues are formed together they make organs, some organisms skip from organs to organs systems to form an existing organism as a whole. Describing how is the cells group is the process of multiplication of cell or the so-called cell division, mitosis. This mechanism of each cell produces another cell that binds together and produces again, repeatedly, to be a larger system called now the tissue as explained earlier. How? Through cell division called, mitosis. Excerpt meiosis - cell division specifically in the sex cells.