The author is quite arrogant himself. What's wrong with looking up solutions for complex problems on StackOverflow? It saves a lot of time and in most cases will end up better than what you come up with on your own, because it has been tested and improved by hundreds of users. And if you manage to find an improvement, share it to make the code better.
Reinventing the wheel every time is stupid and it really seems more like he's the one not able to adapt. When I can do the same things faster and better than you, because I make use of available resources, then I'll be the better choice for most employers, regardless of the age.
Experience is good, but constantly learning and adapting is even more important in this industry and he seems to think he doesn't need to do that.
I took that the author didn't assume that experience (which seemed to be assumed in the article to be positively correlated to the length of career) was the only factor---lack of proper training, including knowing "classics", was also the issue. I tend to agree the latter premise, although I'm not sure the situation is as bad as the author describes. (The author says "I can’t think of a single developer I’ve met professionally who belong to the ACM or to IEEE". Is that really the case?)
IMHO, it's ok to lift answers from SO as long as 1) you know it's a shortcut and 2) when necessary you can trace back the history to the origin so that you can know the original frame the technique was invented and how it was modified along the line. A good solution in a certain context might not be optimal for your context, even though it has been improved by many.
The second point requires a certain level of skill---able to search and read CS papers and implement by yourself or incorporate the ideas into your domain. Without having proper training, it's difficult to acquire that kind of skill solely from skimming SO and alike. But I'd like to assume that graduate-level CS course do give such skill, and by experience you can hone it.
I do note that some answers in SO are pretty decent, with references to the original papers. When I answer online questions I try to do the same as much as possible within my ability and knowledge.
Reinventing the wheel every time is stupid and it really seems more like he's the one not able to adapt. When I can do the same things faster and better than you, because I make use of available resources, then I'll be the better choice for most employers, regardless of the age.
Experience is good, but constantly learning and adapting is even more important in this industry and he seems to think he doesn't need to do that.