It's not that people disagree about which approach is more effective, it's about whether the person cares more about theory or practice (or in what balance, people are not binary). The theory hat doesn't like practice, and says "theory improves practice" as a fig leaf. The practice hat doesn't like theory, and says "practice improves theory" as a fig leaf.

Of course both are important at a global scale. But one person can focus on one side and make an contribution.