Why does baking soda + vinegar work?

To prevent clogged drains, for regular maintenance, several websites and blogs recommend baking soda + vinegar, followed by hot water. Some say this works even to unclog drains.

But, if I recall correctly, baking soda is basic and vinegar is acidic. An acid and a base will neutralize each other. So, I would imagine the vinegar would neutralize the baking soda, leaving something harmless and ineffective.

So, why does this work?