This isn't inherent to IRC; some servers support sending history when you are back online:

* https://github.com/ergochat/ergo/blob/master/docs/USERGUIDE....

* https://docs.inspircd.org/3/modules/chanhistory/

* https://www.unrealircd.org/docs/Channel_history

That's a feature in many people's eyes

Most IRC networks have a MemoServ, so that's not an issue.