The book says: there’s an irresistible pressure to extend the equity of the brand and it’s a mistake. Instead one should create new brands to address new markets/products.
My comment: in this chapter authors predict (in 1993) that Microsoft will fail because they use this unhealthy strategy of extending their brand to new products. 9 years later and Microsoft is still going strong. Looks like the law doesn’t hold universally.
See also Eric’s take