One (of the many) problems with using IRC as a signal is that it's biased towards people with large chunks of predictable free time.
I spend a lot of time communicating with people online, but IRC isn't a channel I use. The problem is that I have a family that naturally consumes a lot of my time. That means I don't control when I'm available to communicate. I get a decent amount of total time, but it's in bits and pieces spread throughout the day (mostly early morning or at night).
That's perfectly fine for asynchronous communication like email, SO, here, etc. But it doesn't work for synchronous things like IRC.
So, using "are they on IRC" as a hiring signal, I believe, effectively punishes people who have families, busy work schedules, or otherwise complex lives. In other words, I think it ends up favoring affluent young people. That's not something I'd personally be keen on biasing for in my hiring process given how much of an advantage that group already has in technical jobs.
IRC is highly asynchronous. It makes it possible to communicate at near-synchronous speeds, however at the base of the technology, any semi-competent developer i work with, even those with 3 kids, are able use IRC consistently, with the only impact being that answer latencies range between seconds and days. Then again, i have the same freedom, so it benefits both sides.
For me, Github is most interesting as a signal in terms of the actual code available.
Lack of Github means I'll have to find another way of seeing example of the persons code, but that's ok. I wouldn't dismiss anyone as a candidate for that.
But someone with a Github repository or ten might be at an advantage because it serves effectively as lowering the threshold: I don't need to find their CV interesting enough to decide to ask them for an example of their code, just interesting enough to look at what's already there.
I spend a lot of time communicating with people online, but IRC isn't a channel I use. The problem is that I have a family that naturally consumes a lot of my time. That means I don't control when I'm available to communicate. I get a decent amount of total time, but it's in bits and pieces spread throughout the day (mostly early morning or at night).
That's perfectly fine for asynchronous communication like email, SO, here, etc. But it doesn't work for synchronous things like IRC.
So, using "are they on IRC" as a hiring signal, I believe, effectively punishes people who have families, busy work schedules, or otherwise complex lives. In other words, I think it ends up favoring affluent young people. That's not something I'd personally be keen on biasing for in my hiring process given how much of an advantage that group already has in technical jobs.