You shouldn't use IRC for low-traffic communications, or more precisely it shouldn't be used in the scenario where you want people to be able to receive messages while not connected to the channel. Email is the appropriate tool for these cases.
I don't control the message frequency or member timezone/presence of existing channels that I didn't create in the first place. Also switching back and forth between email and IRC depending on frequency sounds cumbersome to me. Some niche channels can have busy weeks while being silent on others. I like how bouncers improve the UX for that situation.
