I didn't use that specific term because it sounds as stupid as "rockstar" or "ninja", but when I was hiring recently I only used Facebook ads (which you could target to specific genders or ages, if you wanted - I only targeted by location) and stressed that the job(s) required someone comfortable with the Internet, social media, and Internet culture (which, indeed, they do). I only got applications from people in their mid 20s and younger but found the right people for the job.
I'm sure you feel good about the people you hired, but how do you know that there wasn't someone even better who didn't apply because of the narrow targeting of your ad? If somebody posted their job ad only in the AARP newsletter, would you feel that it had been made available to twenty-somethings? After all, they could read it.
This all goes back to the numbers games in hiring. Targeting the listing is cheaper, and if you can identify a subgroup that contains most of the potential candidates for your opening, it might be sensible to target.
Sure, there might be some "big fish" in a group you didn't target, but so long as you are happy with the people you hired, didn't it pay off? Not every position needs to be filled with a rockstar-ninja-pirate-haXX0r. Maybe all you need is a person who can get the job done (imagine that!)
I actually believe I choose the most widely disseminated approach. My Facebook ad was targeted to within 20 miles of my town and reached around 10,000 unique people according to Facebook. Only 18,000 people live in my town and it's a very rural area. Even our local paper's job ads page gets fewer readers, I bet.
Two of the people I hired actually didn't even see the ad themselves but had it shared to them by other people, so if older people were looking for a job in my field, I believe they would have had a good chance to see it too.
Out of curiosity, if you had received an application from a 40 something who has been "digital" since before the internet was deemed a human right, would you have felt comfortable hiring him?
