Don't listen to this guy. Building relationships is a huge part of how you go grom one of the massive pile of mostly crap resumes to someone who can skip that and get a warm interview. If you have spoken to someone and they remember who you are, you have a relationship. If you develop relationships with people who might hire you later, maybe they don't hire you, but maybe they can introduce you to someone who will.
The EV of contacting people like this is high. You should do it.
I agree with what you're saying, but does this approach scale? What I mean is: (say) Google gets millions of applicants a day. If all of them start calling up Google devs wouldn't that waste a lot of their time? (I guess a reason why this works is that not many people are doing it)
On a related note, I've found that I get a lot of benefit just by calling and speaking to a real person. For instance, an airline representative once saved me nearly $800 on an offer that was not mentioned anywhere else