From the same article :
The trade-off for those perks is that Windows 10 S won't let you install any software that's not from the Windows Store app market, which means that, at the very least, you wouldn't be able to install the Google Chrome web browser.
If you're not down with that, Microsoft will let you switch any Windows 10 S computer, including the Surface Laptop, to the regular Windows 10 Pro for a one-time $49 fee — less if you're on a tablet or something else with a smaller screen. But if you do that, Microsoft says, it can't guarantee you'll get the improved battery life and performance.