Sometimes, but a description of the state of the art in the past does not become a historical tract with the passage of time. The better ones do; others just become outdated.
Well, the ones which fail (and which become outdated) can also teach us valuable lessons : looking at the current state of the art doesn't necessarily tells you what happens if you do things differently.
In other words, we tend to focus on positive results, but negative ones ('don't do this or.. !') can be equally interesting and useful.
