I believe the oil component of a sauce of a pasta sauce, for example is the critical lubricating factor. It is here that herbs and spices will get infused. Wherever the oil goes thereafter so will the flavor from herbs and spices.
When you add tomato puree, the puree itself cannot get absorbed by the oil so significant bits of non oil mixed puree will exist in the final sauce. This will not absorb the flavors of the herbs and spices, so there isn't an equal distribution of herbs and spices throughout the sauce.
Is this correct, or would you say a sauce such as dolmio, or homemade has the oil mixed with and well distributed in the tomato? Put another way I don't think herbs/spices are soluble in pureed tomatoes, so I don't expect a good distribution of the flavour throughout the puree.