In a generic browser like Konqueror, the requirements for integrated components are not as high as with an office suite. In an office suite, different components operate on one single document, whereas in a browser, the components basically provide different views for given Urls. To illustrate this issue, imagine how far the web came with such primitive and inflexible component technology like Netscape plugins. They did most of what people wanted to do with browser plugins, though, and so became a huge success. So let's look closer at the specific advantages of such a solution.
Typical examples are programs written in interpreted languages.
With a pure in-process model, one would have to be able to load the interpreter as embedded language. If a component handles the event loop differently from the embedding application, an complete event loop merger is required. This glueing code can be tricky and might not work well in all cases. Not sure where this is actually useful, but it has most certainly some technical beauty attached to it. Let's pick a concrete example.