Maybe I should explain myself. There was a time when "systems analysis" was used. You evaluate the needs to solve a problem. If you have a web application where you only have a limited number of users and storage size is not a priority, why set up a high availability zillion multi-node servers for such a project. I.e. student testing lab at a college. Everything is in degrees. Secondly. the notion that a single server especially a linux box could not be secure is ludicrous. Sounds like someone who is inept at linux and wants to make excuses. Reminds me of some MSWindows administrators I used to know. Be that is at it may, considering how the highly touted Amazon services have had so many security issues, I definitely would not consider it a stellar example of a robust system at any level. Do not get me wrong I was a Novell, Linux, and MSWindows administrator for over ten years,  so I feel I might have a clue about all this. If you pay me enough, I will use any OS.
By the way, you actually can go from a single server to a multi node set up without taking anything down. The best way is to set up the original server ahead of time with the capabilities, so it is a matter of plug and play. Guess that is all part of the systems analysis to tie it all together.