Chat systems are meant to be ephemeral. The conversation goes away after a time. Logging makes history discoverable, but nothing yet has been able to provide an actionable summary of the transcript.
Slack is getting toward it with its reactions feature, which could be employed consciously by users to mark lines for inclusion in some kind of daily/weekly summary log sent via email. IRC lacks this facility since it lacks a unique identifier for each line. It might be possible to repeat the line to a bot, though, but that seems messy and allows for significant duplication or alteration of what was said.
I personally use irccloud.com for persistent IRC, but mostly for push notifications to my phone.
Slack is getting toward it with its reactions feature, which could be employed consciously by users to mark lines for inclusion in some kind of daily/weekly summary log sent via email. IRC lacks this facility since it lacks a unique identifier for each line. It might be possible to repeat the line to a bot, though, but that seems messy and allows for significant duplication or alteration of what was said.
I personally use irccloud.com for persistent IRC, but mostly for push notifications to my phone.