And and or may be little, but they are fierce: They connect ideas not only in writing but also in math and logic. For instance, Boolean algebra uses and and or to determine the logical relations of compound propositions. These little words also make computers work. Because of and and or, you can send an email, share a selfie, like a meme, and access your bank account.
In fact, recent studies suggest that we should do more to directly teach these and other conjunctions. If developing writers can't use them effectively, they will struggle to formulate and express ideas.