Author mentions that "Szlachta" are now portrayed as the villains of Polish history without appearing to understand why this is the case.
The key to understanding the dysfunction of polish political system at the time is the concept of "Liberum Veto" (https://en.wikipedia.org/wiki/Liberum_veto). Essentially any legislation passed by the Parliament ("Sejm") had to be passed unanimously.
This resulted in nobility securing earmarks and privileges for themselves at every turn and led to anarchy and destabilization of the political system, which culminated in partitioning of Poland between three of its largest neighbors for 123 years.