I don't disagree with your statement but I would have expected an article with "bare metal" in the title to cover some of the unique issues associated with bare metal. Like measuring, planning, and managing capacity.
In my (perhaps unique) experience measuring planning & managing capacity is more of a problem when using VPS's. Bare metal has so much more capacity per node than small VPS's that the minimum 3 node cluster will handle a few hundred small sites before hitting any sort of limit. So why bother measuring. :)
In my experience, adding more VMs when capacity is needed is trivial to automate on a platform like AWS. With real physical machines it takes advanced planning and actual physical work to deploy more machines. Even with a managed hosting provider there is work to do to automate the provisioning.
How so? If I need a new VM I just click (or make an api call) and it's almost instantly ready to go. If I want a new physical server I have to order it and get it delivered to my cage and then have someone rack and wire it before I can even start provisioning. There is a lot more involved in the second case.