OP, this is where everything is headed.
Gone are the days of handing over a solid resume and quietly clocking out at 5pm. All that extra stuff like github and personal branding is the new language of the age. Without participating you look like a cave man to employers.
A fresh out of boot camp novice coder that is at least putting himself out there on social media has a huge advantage over an invisible genius because he is with the times. He's speaking modern english.
A terrible singer on youtube will get hired before the person with a golden voice that is still making 8tracks. Because people don't buy 8track cassettes anymore (quiet, hipsters. I realize my analogy sucks). They watch youtube.
Why are you so resistant to just doing what it takes to communicate in a way that is understood in this internet age?
How do you suppose people should respond to your rant? There is a lot of resentment and entitlement in your voice. That will not get you far in life.
There is an implicit question that begs answers. Are the people making the hiring decisions so incompetent that a person with minimal knowledge and experience is able to bamboozle them into getting a job whilst a more competent person with a good track record gets overlooked? I often wonder whether it is a pay peanuts ... situation.
The stuff you refer to is what employers use as a proxy for showing that you do more than go to work and switch off.
I must admit I had similar if not the same feelings about the trends in tech these days. Everyone is a geek who can write a piece of code and write a patch. I see entitlement attitude in most young software engineers and utter disrepect for people who took time to refine their craft. But this is something we cannot do anything about so why worry ? If its bothering you, you should try to explain it to them.
And let's be honest here, regarding your "code rockstar" comment - it's getting harder to demonstrate ability in the age of over sharing and over communication. Internet can be a place with too much noise.
But Internet has also enabled us and empowered us so much. Instead of fighting the culture of show-offs, why not contribute your experiences on a blog ? The positive ones ? Build an online reputation and take advantage of the same infrastructure that many abuse ?
If you are really good at what you do, people will notice you. You don't have to show off and make loud noises. Just showcase your sincere works and get on the flow. You may never know what wonders could touch your life.