When fish are actively feeding, or in cleaner water, yes, a natural bait may be the best choice. But when the bite gets tough, they are not actively feeding or in dirty/stained water, there are baits that can make fish bite.
This is called a reaction bite. Bass don't do much other than eat and make more bass. They are programmed to eat so when they are alarmed or curious, (and because they don't have fingers to examine a bait) they just eat it.
Now, there are tons of vids showing bass hitting a bait, and then spitting it out. This could be because they were curious, ate it, figured it out and a non-food source, then spit it. We don't care about that because we want to set a hook before they spit it out; as long as we can trick them into biting in the first place.
This is where scents on baits can be useful too; to make a fish hold a bait just a split second longer so we can set a hook.