So, firstly, everything this guy got was freely given. There was no expectation of reciprocation, so he doesn't owe anyone anything. That's part of the beauty of the internet gift economy.
But, i bet that he has given something back. Maybe not contributing content of his own. But has he ever voted up a post? Voted down a comment? Flagged something? Reported a bug? Enabled usage statistics reporting in some software? All of those are tiny, but non-zero, contributions to making the web better.
Well, I expect zero lurkers to actually respond to this, hehe.
Even if you're not, you may very well be sooner than you might think just because you'll be training yourself to be so. Also, if you found something interesting, odds are in your favour than someone else will too.
So, take a chance and jump. But don't do it for others, do it because you want to.
You shouldn't be wanting to give back to the internet, you should be wanting to give back to other people.
So long as you're a genuine-at-heart and mindful person, this should be a regular occurrence for you regardless.
Every human interaction you have is an opportunity to give back :)
Not saying that everybody should start a blog or that most blogs are not garbage written by people that don't have anything interesting to say. But if you want to take your career further it's probably a good idea to immerse yourself in your professional community in a way that expands your reach further than your near friends and co-workers. A blog can be a way to do that.
The post speaks about "owing something to someone" but this holds even just by purely egotistical measures.
Generally though, I feel I don't have anything profound enough to say to add to the noise that already is the internet. I don't mind people who do add noise (as long as I'm not forced to consume it).
I have a dev blog I post to every 2-3 months. Nothing regular, but if a thing costs me a lot of time to figure out, I'll write a post and hope it'll save others time when they search for that particular topic.
I think this is really the only way for most people. Nobody knows me, nobody gives a shit about me, why would they follow me as a person?
Giving back to the internet is a good thing, but only if the stuff is read by someone. So either post in a community or have your blog be found through Google.
Everything else is just noise.
I do feel that I would have a fair amount to share back of what I learn. However, when I think about the limited time we all have to live, and how nasty people can be online for even the most trivial matters, I always reach the conclusion that my time is better spent learning. As an Italian friend of mine used to say, “my objective in life is to die wise”.
It's quite organic, never a deliberate decision, but I guess if you find a particular community very rewarding over time you may slowly grow comfortable enough to contribute very actively.
No, not when it comes to the decision not to have a blog, or a facebook page, or a twitter account, or a non-throwaway HN login.
Others may disagree, but I see profound narcissism in the popularity of these (plat)forms of expression, which are mostly about signalling.
If you feel guilty about "not contributing" then contribute in some meaningful way. Contribute features, support, and/or bug fixes to open-source projects (or start one from scratch if you've an unreachable itch.) Teach people how to do stuff. And have enough self-confidence not to need to "share" literal or metaphorical selfies.
Those that are not, I don't find that they get in my way too much. If someone wants to keep what amounts to an online technical journal... search engines are pretty good at filtering chaff.
I do not participate in those social activities, but I don't consider it a great virtue that I do not. It would probably be good practice for writing documentation for my fellow developers.
 Cloudflare and randomascii's blog posts being some of my favorites; and I don't think the motivation is much different if at all.
When I was a child, I was of no high opinion of 30+ plus adult men with families wasting time on vain talks in place where their opinion mean nothing. Now, I myself will soon become one of them.