It feels like over engineering for most projects, and yet another thing for new hires to learn.

I can't judge Twitter's design without seeing it, but I don't like the sound of this:

"the simplest web page on twitter.com requires collaboration of dozens of network services speaking many different protocols"

Simplest page? Dozens of collaborating services? Many different protocols?

I'm skeptical this is the most elegant architecture possible that meets the requirements of their simplest web page.