I am sure you would agree that we use the above statement atleast couple of times a day, especially if you are a project manager in one of the software companies. A few years ago, while I was interacting with Craig Larman, he mentioned that "human beings" are not fungible resources, they cannot be called as "resources". That was the first time I learnt that ugly side of calling programmers/software engineers as "resources".
The word resource, in the past was widely used to mean things that are "replaceable"/fungible. For ex: A broken chair can be replaced by another new chair. Another interesting feature of a resource is, you can start using it immediately. Ex: Once you buy a new chair, you can start using it from the next minute.
I don't know from where it all started. However I have been hearing the usage of the word "resources" implying mostly "people/programmers" since several years in the software industry. When we hire a new programmer, we say that the new resource is being hired in place of the old one. We are aware that two human beings cannot be same, one "developer" cannot be replaced by another cloned "developer" with exact specifications. They are two different people coming from wide range of experiences, even though they have "similar" work experiences and designation.
So, let us consciously stop calling "human beings" as "resources".
Here are some more people who think on above lines