Question

why cannot all multicellular organism Divide by cell-by-cell like sperogyr

Answer 1

Multicellular organisms cannot divide cell by cell because of the following reasons:
Multicellular organisms contain a large number of cells. So a large number of cells divide simultaneously. They cannot survive by cell to cell division.
In multicellular organisms there is division of labour. Each cell performs different functions and divide at different time points and at specific spaces. So, cell by cell division is not possible.