GMAT Strategy

3.2 Analysis of an issue
"Since no business can be all things at once, companies that specialize in one product or service are more efficient than those that offer a diverse product mix."
'Jack of all and master of none' is very much valid when applied to any business. If one wants to run business he has to be the master in his domain. I completely agree with the author that companies with diverse product portfolios often proved to be less efficient than the companies with specific single product.
The company has to keep itself aware and update its knowledge base in the area in which it is active. It's always easy to keep track of the advances in single area of expertise than in many. To cope up with the changes in the product companies often need very agile management system. If there are multiple products the nature of simple problem becomes variegated and often becomes confusing. Best example of the fact is General motors, the giant company has many subdivisions and multiple product portfolio but due to economic recession they had to bear losses and ultimately has to shed off their few divisions which was responsible for few products.
One offer far better products if one decided to excel in the limited product base. They say that if one can see there is always a complete number system between 0 and 1. Best example of this type of company is Apple. Apple has limited product portfolio and their each product is really an apple of one's eye. The company creates history by launching their Iphone which ultimately changed the lifestyle. Such companies can offer their customer much more satisfaction for the cost of money customer paid.
Company with single product can excel itself faster as compared to other companies which don't follow this strategy. Such singularly focused companies can create monopoly of their product in the market and literally dictates the markets. Google, Apple, Microsoft, Pepsi, are some of recent the examples of such type of companies. As successful they also gain the creative advantage and offer customer much more as compared to others.
In sum, I think that to be the best in one single area of expertise is always much better than creating different avenues of expertise to survive in them.

The last(closing) paragraph could have been a bit more descriptive. A solid conclusion backed up with good examples which you have already put could make this an excellent essay.
You are among the bold people who did not oppose what the Author said, with usually is the case.
You deserve atleast a 4.5 or more.