What does competition in the office apps get you? Chaos.
That statement is mistaken and highly misleading. It is nearly 180 degrees
diametrically backwards.
Theory: Insurgents have every reason to be compatible with the market
leader. If they introduce an incompatibility, you should assume it's
accidental. The monopolist, in contrast, has every reason to churn things
in order to introduce incompatibilities.
Fact: Microsoft has been found guilty of intentionally doing this.
Note that the appeals court upheld these findings of fact. (There is some
question about what the _penalty_ should be, but that's a separate question.)
Fact: In a non-monopolized situation, there are such things as
standards. There are such things as iterop conferences and bake-offs,
where providers meet to work out any inadvertent
incompatibilities. Example: several of my friends are going to: http://www.vpnc.org/bakeoff.html
This generally results in a very high degree of interoperability.