I would say chat history and asymmetrical scheduling for chat are expectations in this day and age, and the lack of them is one of the biggest reasons people find IRC irritating or difficult. (I ask a question, and if the person fit to answer it isn't logged in right now, it never gets even responded to.)
Every fairly modern chat solution, Skype, Discord, Slack, etc. allows you to see messages while you were offline. Compared to things from the older eras of messaging like AIM and YIM, when generally you couldn't even message someone unless they were online as well.
So it's not surprising to me for IRC loggers to be a relatively more modern element: They're filling in a gap IRC has with modern chat clients.
ZNC and earlier implementations have been around for 15+ years to provide queuing proxies. Pretty much all of the "unique" features found in current chat systems were also implemented in one fashion or another in the IRC ecosystem decades ago. Ease of use has definitely improved, in exchange for for-profit company control over communications in these systems. IRC's decentralized nature still argues for its relevance even now.
IRC is not really decentralised, is it? Or are you arguing that it’s decentralised in the sense that each user can implement and control some features like logging?
You probably did without realizing it. A persistently logged in user (through e.g. a bouncer, or just someone not rebooting too often) is essentially a logger. Those logs are private by their nature, but where I IRCed it was common for channels to each have their own logging bot.
Every fairly modern chat solution, Skype, Discord, Slack, etc. allows you to see messages while you were offline. Compared to things from the older eras of messaging like AIM and YIM, when generally you couldn't even message someone unless they were online as well.
So it's not surprising to me for IRC loggers to be a relatively more modern element: They're filling in a gap IRC has with modern chat clients.