Are we decentralized yet?

For smaller semi-private circles IRC especially with web front-ends that provide scroll-back are still great but in my experience when they get too big there is just too much politics and too many cultural differences and things start to fall apart much like agilob's example. IRC is still great for groups of like minded people that do not need to bring in the entire world into their tent. In the early internet more people were like or similar minded and so it worked well for the most part. Some would even argue it still works great for the general public but I am not so sure. Keeping web interfaces semi-private with simple-auth and disabling referrers reduces the risk of botters, agent provocateurs and other forms of riff raff trying to sow division among people, or third party AI bots snooping or arguing.

NNTP is also great but most people can not afford individually to mirror entire binary groups and most ISP's no longer perform this so most people just use commercial news feeds if they want binaries or one of the free NNTP / Usenet providers if they are just using text. People can certainly peer with some of the free providers [1] and probably should to reduce the risk of people being censored. Much like IRC people can create their own little private or semi-private linked NNTP servers to replicate a distributed thread based forum of sorts.

[1] - https://www.eternal-september.org/index.php?showpage=peering