Use only an external display but keep the MacBook lid open

While Windows does, macOS doesn't allow switching off the laptop's own display while the lid is open in order to use only an external monitor. The closest workaround I've found is the following:

1. Open System Settings.
2. Go to Displays.
3. Select your built-in display.
4. Use as: Mirror for [your external display].
5. Optimize for: [your external display].
6. Brightness: all the way down.

Why this works better than closing the lid

• Touch ID still works.
• The speakers don't sound muted, as they do when the lid is closed.
• You can still use the MacBook's touchpad and keyboard.
• The mouse cursor doesn't jump to the other display when it passes the screen edge.
• The GPU still renders for two displays, but it doesn't have to render two different screen resolutions or aspect ratios.