It is correct, just slightly misleading. The size is made to look like the browser default size taking display density into account. It is adaptive.
The 16px font, in the screenshot you send, is not "browser default size". Or, it is, but not as it was intended by browser makers. See, when it was chosen as default, we used 14" 1024x768 monitors or worse. Anybody who wants to show this as it was intended, needs to take account the DPI of a modern screen and increase the 16px accordingly.
Trust me, those guys have gave a lot of thought into readability and font sizing.
>Such huge text is definitely not easy to read for me on any of my devices.
Actually it is. You are just not used to it. Whereas you are used to fonts of exactly the same size (or very near) when reading books. Some people have been conditioned to stare at tiny fonts (a 12-14px font is a monstrosity on a modern display) and proper type jumps at them. Check also Zeldman's reasoning:
http://www.zeldman.com/2012/05/18/web-design-manifesto-2012/