There have been several questions lately along the lines of "Is X a functional or non-functional type of testing?". Although I understand the distinction, it's never been an important distinction for me in my career. Either I was on a team that only did one type of testing, or I have been the only tester on the team and responsible for all types of testing (and I didn't make a big distinction between functional and other types of tests).
What are the pros and cons of separating functional tests from non-functional tests? Are the concerns usually more about dividing work in a team, organizing test suites, applying different policies for different types of testing, or what?