With the Polish, are you referring to the fact they insisted on a weak King, which made them vulnerable to being swallowed up by Germany, Austria and Russia?
More than that.
Look up “liberum veto.” Every member of the Sejm could not only absolutely veto any measure, he could dissolve the assembly at his will! Which invalidated any measures already passed!
This allowed the aforementioned German, Austrian and Russian Empires (and others) to meddle drastically simply by suborning or bribing a single member of the assembly.
A spectacularly effective recipe for destroying your country, at least if it’s surrounded by rapacious neighbors, as every country in Europe was.
The astonishing thing is how long the Poles managed to struggle along with the incredible handicap.