Not to mention, we know how to build structures that can last 1,000 years because it has already been done before! Using a dubious material in place of a known good one is not the best engineering approach.
How many buildings of the same type didn't survive?
If your goal is to use a method that has _any_ chance of success, however small, then the old ways are probably a good bet. If you want the highest chance of success you should probably at least evaluate new methods.
Just because some humans somewhere figured out something in the past doesn't mean that humans somewhere else today know how to do it. Lots of knowledge has been lost to time.