The biggest "issue" I have with IRCv3 is that /chathistory hasn't been ratified yet, requesting the last 10-30 messages from the server logs should be fairly trivial to implement. Yeah bouncers exist but I'm honestly too lazy to set one up and I don't want my computer running 24/7 just to store random IRC messages.
Then again the culture is different with IRC versus other platforms and people adapt with not having a full chat history, so dunno if this is an actual issue in the long run.