It's an interesting view to stand back and look at how training/working out has changed over the years.  One of the main knocks on CrossFit is that they are not willing to "change with the times."  The answer is certainly not clear, but there are many aspects of CrossFit methodology that seem to be timeless.  Take for example the three foundational categories of CrossFit movements:  Weightlifting, gymnastic (bodyweight), monostructural (can call cardio for simplicity sake).  When you combine these three groups of movements into a workout and bring legit effort, the efficacy of stimulus is second to none.  
Todays workout is a great example of a CrossFit workout that could have been programmed 15 years, and now using the same methodology it was programmed today to make for a killer workout.
Here is Cameron and Alli going through a classic CrossFit workout.  


5 rounds:
5 shoulder press
5 push press
5 push jerk
15 box jumps (24/20in)
400 meter run
- rest until the 6 minute mark