Are resumes relevant for hackers?

Yes, but don't obsess about them. Prospective employers will usually ask for a resume. They won't read it very carefully. Remember the cardinal rule of resumes: the only purpose of a resume is to secure an interview.

If you work for BigCos or as something in tech other than a developer, Linkedin might matter as much as your resume (you still need one, though). If you're a startup dev, Github can have a similar impact.

It's not a case of "relevant for hackers" vs "relevant for everyone else" but how you source jobs.

If you're getting jobs via your network then a resume will largely be unimportant, if you're applying through formal channels then you'll likely need a resume.

Portfolio based resumes are mostly popular for more creative roles such as designers than for hackers at the moment. Even if you're supplying a link to your github it's still likely that a potential employer will check your Linkedin.

It's unlikely that an employer will spend a lot of time routing around in your github account to evaluate you so you still need to show up front that you're worth spending the time to evaluate and the best way to do that is still a cover letter or a resume.

Depending on the company/country, resumes seem somewhat irrelevant.

I've noticed a lot of startup or otherwise young high-tech web/IT companies that simply ask for your GitHub account.

In the country I live in, you need a resume and a degree (even if your degree is taught you nothing about something like MVC).

I would also suspect that the bigger a firm grows, it becomes more difficult to:

"hey, I saw you write some awesome Rails gem for automated mailing, my firm needs you."

HR processes and bureaucracy are to blame. Then again, no firm wants to deal with a part-time drug-dealer on their payroll when they have 5000 people to manage.