The Facebook timeline acknowledges that many modern displays have more horizontal real estate than vertical real estate. The design reflects this. It uses much larger visual elements (boxes) than a line of text which means it maximizes its use of both vertical real estate and horizontal real estate.

The other thing you're not considering is that Facebook displays more than just text. If you're displaying images inline as well as text, it's going to be more compact if you interpolate each post in a zig-zag fashion rather than making posts vertically serial.

The example you provided doesn't really illustrate why timeline is bad for a website because it's an example provided in a completely different context.

tl;dr Website design is not command line interface design.