This (fantastic) paper is cited in the Google Megastore paper [1] and we actually use the term "entity group" in our product [2] indirectly because of it. Pat Helland is always worth reading; thanks to the submitter for the reminder.
I would need to read it again, but it smells a lot like high platform availability combined with small traffic, and it looks like a pita to support it (except for the cases where they refuse to support the customers)
It is really worth reading for anyone doing any highly scalable services (micro or not). This article just pin point any issue we have stumbled on in my current job.