The question is a bit theoretical, so I'll start my answer the same way: In theory, or in some projects, testing can be all about generating the great test ideas that will find the most relevant issues. A bit samy way that in theory, or in some projects systematic way of working with requirements will find all the relevant issues and prove that system works the way it is intended.
For the example, the financial domain, the customer most probably will want to know what has been tested and to what extent. That will meant that with some sort test management practices are needed. When to test ( with the great ideas ), when to re-test, how to work with issues and so on.