A given channel, or even entire networks, would often start out pretty free. Dissenting discussion and arguments were allowed, if not encouraged. Users could hold and share their own beliefs without fear of repercussion. It was generally a fun experience. The channel or network would see growth.

But as the community became larger and more established, certain users would often end up becoming ops, and they'd start to enforce their own beliefs upon the entire community. People would start getting kicked or banned unnecessarily for very minor "violations", which most often involved just holding a different opinion than an op.

These kicked or banned users wouldn't come back, those users who liked them would have less incentive to return, and eventually there'd be more people getting booted or leaving than there would be new people coming and returning. The channel withers. If this happens with enough channels, the network withers. As networks wither, IRC itself withers.