"it was kind of inevitable once Poland stopped being oppressed by its neighbors"

No. Not at all inevitable. Poland might have descended into kleptocracy, e.g. Hungary. That this did not happen is worthy of investigation. I'm not holding my breath however; the findings would probably not be welcome.

"A general lack of ideological 'mind viruses' that seem to plague the western world"

Indeed. Poland frequently disappoints the rest of the EU with its stubborn indifference to obligatory Western moral panics.