Dude I'll bypass your first sentence, because you're young my friend and have much to learn about economics (should you take the time in future studies).
You are correct in that Marketers and Economists basically discount the effects of each others field/roles.
However Economics isn't as stade as you think and if you ever do take more advanced courses you will get techers who can give you better more modern examples to make you understand that theory is moulded by practice (just like marketing). Economics can even be used to describe how politicians make decisions and in many cases politicians use political economics (different from monetary and production economics) to influence FUTURE votes, and political actions.
There is a difference between theory and practice, but that's because unlike things like chemistry and physics there's the human factor that is involved. Irrational, emotional, and unpredictable. You add chemicals and a catalyst you can guarantee the same thing will happen everytime. Same thing with physics. The main reason, externalities are excluded. With economics, it's almost IMPOSSIBLE to have a model that doesn't have external factors/forces. Ceteris Paribus is a common saying in economics, it means 'All things being equal', and unfortunately rarely do we have all things being equal.
It's not clear what you're saying with your 'bullets'. I think one of the things you need to realize when comparing marketing and economics is that makreting is used to predict/understand consumer actions, and economic theory is used to understand/predict production aspects. They may seem like disparate entities, but really they are the opposite side of the same coin.
Truely you have to know the role of each and how they fit into the whole system/economy.
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