Hi!
Depends on how you define easy. http://bots.wmflabs.org/~wm-bot/logs/%23mediawiki/ is a recording of everything in #mediawiki by date, oldest at the top, newest at the bottom. I would consider that fairly easy.
It's easy if your use case is "reading everything on a particular day". If your use case is "locating that part where John and Mary talked about FooBar", it's not easy at all. Raw logs are as usable as... well, raw logs. People do read raw logs from time to time, but usually they employ tools to make sense of them - e.g. kibana, etc. Of course, it's a bit strained analogy, but my point is IRC raw logs are not a very good UI for many use cases. Don't have a good solution for this, as IRC is still excellent as transient quick discussion medium, but much less as a long-term persistent discussion one. OTOH, maybe that should be done with wiki+Flow?