When you have to be sure of a statement that is made by "everyone", if you can, is trying to check it for yourself.
And you can do something in your statement: just read Wordpress source code. Some modules are good, some are a mess, some others are just normal. But all of them compose a great blog system that are used by thousand of people around the world that are more interested in writing good stuff instead of complaining about "how ugly" is a particular source code. In summary, the Wordpress creators have a shippable product that is useful.
In the end, it doesn't matter. If you want a perfect blog system, you can always write one yourself.
