Up until about 7 months ago I was on Freenode and then Libre IRC all the time, for years. I don't remember anything about decentralization on there. This was an import thing for me as I was writing a personal decentralized media sharing application.
The best model for decentralization I found was WebRTC. The best explanation on Decentralization comes from Vitalk Buterin: https://medium.com/@VitalikButerin/the-meaning-of-decentrali...
Before going further you have to understand that decentralized is different than distributed (federated). Distributed means fault tolerant redundancies with various degrees of independence/autonomy. Discord and Bitcoin are distributed as they still have a central point administration whether its a public ledger or username or whatever.
Decentralized really means strongly separated. For example if I wanted to communicate privately with my wife ultimate privacy means not through a third party server, but directly from my computer to the wife's computer (but encrypted relays are fine when required to compensate for transmission limitations). Accomplishing this requires decentralized transmission, which is tough to engineer even after solving for NAT.
Have fun.
