All those political bannnings by admins aren't really the big issue (and only relatively recent). The big issue re: reddit and free speech has to do with things that Reddit corp has trouble monetizing and putting ads beside. Sure, some of the bans might come from a partisan political place but the vast majority of reddit admin actions are just that of corporate drones protecting corporate image in order to make more money.

Centralized corporate run proprietary systems will always end up like this. It's the circle of web life.