Why use Complex-compound sentence?

Question

As in, why to famous authors uses them in their works?

Answer 1

Erika, good writers know that it is important to vary the length and complexity of sentences.  Therefore, they mix simple sentences with compound sentences and compound-complex sentences.  It adds interest to the material.

Answer 2

Successful writers know how to blend complex-compound sentences with simple sentences. Complex-compound sentences are more challenging to write, but are better at expounding profound concepts.