It's not. It's a big factor in how positive it has been. Will "such conditions" (lowering rates a large amount and "print-money") continue to be the same in the future?
The back testing of the data goes back to 1993.We have seen three bull and two bear markets during this period. In my opinion that's a pretty good sample....One thing i have noticed over the past 18 years of following the markets. Nothing really changes a lot. There are noticeable and repeatable patterns.
If there is one thing that is a detriment to the markets it's algo program's that react off printed text from the financial media.