From a practical perspective, it seems to me that the Beer Game rests in three parts: in imperfect information, time delays, and most importantly, independence of agents. If each member of the supply chain knew consumer demand perfectly far enough in the future, they could compensate. Likewise, if each member of the supply chain could instantly scale their process, they could compensate. The key, though, is that even…
Since you don't know the demand - you need a responsive, high bandwidth, system.
Having suppliers that can't respond quickly - either because they are a 2week container ship voyage away, or they take 3months to respond to quote requests, or they think they can make more money by demanding huge penalty clauses for any changes in order - all these add resistance and slow the response.
There is also a cost consideration. Once you start making a component it is costing you money until the consumer pays for it. Having to make a billion $ worth of screens/chips/cases 2 years in advance is costing that whole network of suppliers money - costs which will be passed onto the customer