Some key reasons are:
Synthesizing allows you to demonstrate your critical thinking in your writing. By identifying similarities and differences between theories, methods, studies, findings, etc. and making these explicit to the reader, you are presenting ideas in relation to a wider context and in a more complex manner.
Check Bloom’s Taxonomy below and notice how concepts such as organise, relate, compare, contrast and distinguish are considered higher level thinking skills, compared to list, state, describe, etc. You can hover over the question marks to learn more about each level.
Here are a few things worth considering: