Hopefully you cook, because I'm going to use my spaghetti sauce analogy again.
You can make really good spaghetti sauce by buying a jar of Ragu and throwing in a couple of fresh ingredients like basil, mushrooms, and garlic. It'll be tasty and reliably reproduced. However, you can't closely control the nature of the final product since you're dependent on the Ragu which makes up the majority of the flavor.
By starting from tomatoes, olive oil, salt, and pepper you can precisely tailor the final outcome (if your process is good). It will be difficult to get "just right", and not easily reproduced (that's part of getting your process down) but the possible outcome is well worth the extra effort.