The book says: in the long run, every market becomes a two-horse race. McDonald and Burger King. Coca-Cola and Pepsi. Nike and Reebok. Crest and Colgate.
My comment: even if that was universally true, how does it help a marketing person? There’s little a marketing person can do about the position of his company in the market. The only conclusion I can make is that if I were a marketing person and worked for No. 3 company, I should just quit and apply for a job in No. 2 or 1.
The other problem is that it isn’t universally true and the book again makes a big simplification of reality and it tries to support this simplified picture with selectively chosen examples. There are market where 2 brands can’t fulfill all the demand (there are more than 2 well-known car manufacturers). There are markets that tend to fall into monopoly (e.g. Microsoft has 95% of operating system and office software markets). I’m sure there are many markets that are two-horse race, but then again there are also three-horse race markets as well as highly fragmented markets. This “law” is nothing but a sometimes true observation and it’s not true frequently enough to be worth anything.
See also Eric’s take