For some products, yes, user shadowing, interviews and testing is enough. But in the case of VS Code, I agree with the other commenters that you can benefit fr

For some products, yes, user shadowing, interviews and testing is enough. But in the case of VS Code, I agree with the other commenters that you can benefit from both. VS Code supports many languages, source control systems, workflows, external systems and extensions, and it's used by a very wide spectrum of users and developers. I can see why they believe telemetry is required to better understand how it's used.