Because they are using exagerating as a way to give more power to their point.

This is from one of my previous economics classes. It explains what characterizes a monopoly.

Sorry, but MS was found guilty of monopoly in 1999 and although the appeal overturned the decision to break MS in two it didn't overturn the finding that MS was a monopoly. In September the dept of justice under Bush admin decided to give MS a lesser penalty. 

"Judge Jackson issued his findings of fact^[11] on November 5, 1999, which stated that Microsoft's dominance of the personal computer operating systems market constituted a monopoly, and that Microsoft had taken actions to crush threats to the monopoly, including Apple, Java, Netscape, Lotus Notes, Real Networks, Linux, and others. Then on April 3, 2000, he issued a two-part ruling: hisconclusions of law were that Microsoft had committed monopolization, attempted monopolization, and tying in violation of Sections 1 and 2 of the Sherman Act, and his remedy was that Microsoft must be broken into two separate units, one to produce the operating system, and one to produce other software components."

MS was also found guilty in Europe and had to pay 1.35 billion USD in compliance with the rulling in 2004. 

a monopoly is a company with more than 25 percent of the market share

It should be pointed out that not every economic theory agrees on what makes a monopoly. The most narrow definition is "supply of a good is owned wholly by an individual entity." Most practical economists prefer "a single entity owns most or all of a market for a good."

The classical end result of a monopoly is less supply of the good in question. Assuming relatively inelastic demand, reducing the supply of the good drives up prices. In other words, if most people still need a product but the supply of that product goes down, then the people who need it will try to outbid each other by paying more for it. If a monopoly did not exist, other market entities would simply increase their supply to satisfy the demand and bring prices back down. If a monopoly does exist, the price just goes up, and even worse fewer people were able to obtain the good.

@ johntonsoup, that's some nice economic reasoning. However, you're making the one classic assumption that always trips up Economists - you assume that all companies are greedy and immoral :P

^^

Gordon Gekko broke their hearts...

If a monopoly is a business that has more then 25% of the market share then both nintendo and microsoft have a monopoly over home consoles lol

A board game with many variations

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