To a certain extent, I believe they are. The most striking example is probably the 2002 WCF. Btw, I believe the draft lottery is rigged as well.
Question is, why do I still care? Don't have an answer tbh. All I know is my interest is fading year by year. I mean, the C's have made the NBA Finals for the first time in 12 years, yet I didn't even bother to watch Game 2. I watched the first 3 quarters of Game 1 on tape delay, only to fall asleep early in the 4th quarter.