Rejection isn't necessarily failure. I appreciate that the article is about objective self-evaluation and self-improvement, but that requires a good understanding of why you really didn't get the job. And it's possible the feedback you are getting is not the whole story.
Back in 2003 I was a young C++/C/Java developer with a couple of years of experience looking for a new job in a new town. I felt like I was talented and capable and was hungry to prove myself. It was a tougher market in those days so I was applying anywhere that posted a job that seemed like a fit. I got rejected time and time again and most of the time I didn't even get a rejection. I never even heard back at all. I was ignored. It was demoralizing.
I knew if I could just get an interview, I'd have a great shot at a good job. But I couldn't even get an interview. I felt like a failure.
I finally landed a C++ gig at a company I accidentally applied to twice (they gave me an interview because they thought I was resilient). It turned out to be a great experience. I got to tackle hard problems, learned a lot, and was promoted quickly. I was soon managing the team I was originally hired to write code for.
After a few years of that I was headhunted to work for a consulting firm that specialized in what later became DevOps (we were pushing CI/CD back in 2006 and automated virtualization for build and test in 2007). As part of that job, I ended up with a few gigs at companies that had rejected me only a few years before. Here I was telling them how to make software at 4 times the rate they could have hired me for full time just a few years earlier. I'd won!
But really, I learned most of these companies hadn't hired me for reasons that had nothing to do with me. I didn't know who I was competing with. I didn't know what specific traits they valued. I didn't understand the stresses and risk and pressure those hiring managers were under when they compared the PDF I submitted to the PDF someone else submitted.
For example, the company that hired me after I applied twice rejected me first because I was from out of town. They had so many bad experiences with hiring and firing that they didn't want to hire someone that had to move to take the job. They were actually being considerate of my risk, not just their own. They thought they were doing me a favor!
And in a few of companies I was now consulting for, I saw poor culture, poor talent, poor processes, and poor hiring practices. I saw HR people filtering out prospects because that person's resume didn't have everything on some magic, unadvertised checklist. I saw politics. I saw bias. I saw incompetence. Some of these places wouldn't have been able to spot talent if their lives depended on it.
Really, I wasn't the one that failed when I was rejected. They had failed by rejecting the wrong people. And I was fortunate they'd rejected me because it would have been an awful place to work. Rejection is God's protection, I've heard it said.
So rejection wasn't failure. It usually had nothing at all to do with what I really could do or couldn't do. If I failed, it was in allowing rejection to affect my self-worth.
After running my own business for almost a decade, I'm back in the software industry. I'm fortunate to have a good job thanks to people I worked with previously, but I'm hungry for bigger challenges and believe I have the skills and capability to meet them. Except now I have a 9-year "hole" in my resume that doesn't say Google/Microsoft/Facebook or AWS/Azure/Cloud or whatever else the cool kids are doing. From a hiring manager's perspective at those great jobs that attract lots of talented candidates, that means I'm a risk. But having been that hiring manager, having owned my own business, and having spent time in the trenches, I understand and sympathize. Rejection isn't personal and it's not always about me.