It's an interesting thought, and the other side of the coin might be the assumption that all the various gods are just manifestations of the same God/entity/whatever, who has appeared to different people in the form(s) most suitable to their historical and cultural contexts.
Were that the case, however, it seems strange that the same being would demand more sacrifices of some than of others, or place stricter guidelines on one group versus another. (Though perhaps God is a behavioral economist, after all, and he's simply structuring different incentives for different groups, i.e., creating the frameworks the different groups need most? But, to your point, that wouldn't account for why some groups and gods died out altogether).
Were that the case, however, it seems strange that the same being would demand more sacrifices of some than of others, or place stricter guidelines on one group versus another. (Though perhaps God is a behavioral economist, after all, and he's simply structuring different incentives for different groups, i.e., creating the frameworks the different groups need most? But, to your point, that wouldn't account for why some groups and gods died out altogether).