Jan Kazimierz ruined Prażmowski's plans of vreforms of Sejm in the name of vivente rege ( sejmiki had instructions to accept all reforms, except for VR, while King wanted only VR, and could give up other reforms, which were really needed, he and Queen, no one else were responsible for it. Sobieski's reign was after that disaster, at the moment, when it hardly could be reversed (and Sobieski himself, despite being excellent commander was incompetent as politician). King of PLC really had enough power to make serious troubles and Jan Kazimierz often used it (King's supporters have broken Sejm and blocked taxes to raise army when Russians invaded Lithuania in 1654 because King disliked Janusz Radziwiłł). JK was not innocent victim of the System, he was the man, who ultimately skewed it. After Civil War any initiative of King was seen by nobles as secret attempt to impose Condé on the throne.