At the beginning of the century, people played around and gave all kinds of things URIs like "http://example.com/foo.rdf#color".

for one reason or another people demanded the right to be able to use http://example.net/people/Pat to denote Pat rather than a web page about Pat.

The term Resource is indeed enough for REST, but other use cases such as RDF already reserved Resource for something different.

in fact in RDF the resource was allowed to be anything at all. A class, rdf:Resource even used the term as the universal class of all things.