Answer:
Because improvements in microscopes reveal new information about the structure and function of cells. This makes concepts of cell theory outdated and incorrect, generating the need for revisions in cell theory.
Step-by-step explanation:
Over time, microscopes have become more powerful and better, allowing images of microorganisms and cells to be viewed with increasingly better qualities that allow new information to be developed. In relation to cells, specifically, microscopes allow things that were not previously seen to be seen in great image qualities, allowing new information about the structure and functioning of cells to be discovered.
When this new information is discovered, some old concepts defended by cell theory become obsolete and imprecise, which means that these concepts must be realized and, if necessary, replaced by new concepts.