Agreed. Up to a certain point, a single server is going to be considerably more cost effective than multiple machines, as well as requiring less devOps time.

Agreed. Up to a certain point, a single server is going to be considerably more cost effective than multiple machines, as well as requiring less devOps time. (Especially nowadays when you can easily lease a server with, say, 16 cores and 48GB of RAM.) I can recall having to restart our production server exactly once in the past 12 months for a kernel update. Every month would be an irritation for sure.