Med school is difficult. An internship is difficult. A fellowship program is difficult. Undergraduate degrees are a rubber stamp, CS included.
There are 20k oncologists across all fields of oncology within the US. That's also about the number of engineers Google employs. Most other industries we like to compare ourselves to are leagues above ours in individual merit. My father is an oncologist, and I'm reasonably confident he has some familiarity with every genitourinary oncologist in North America, Australia, and Europe. More importantly, he's on a first name basis with all of their educators. When he needs to hire a new doctor, he doesn't post an ad on health stack exchange. He makes an offer to a specific individual who he already knows.
One thing that we as an industry fail to understand is that we're not special. We desperately claw to it in these conversations. I'm willing to admit it: I'm easily replaceable. Very few of us have any name recognition that exists in other fields. I worked in finance for half a decade before moving to software. When I'd go to interview, people already knew who I was because of the basic human interaction I had as part of my job. When I walk into the door of my next interview, the only thing people know about me is what's on my resume/blog/stack overflow answers.
Personally, I find technical interviews to be a cheap and easy filter. You may not always get the best person from your pool of applicants, but you get someone that's better than most of them. The marginal benefit of one vs. the other is rarely meaningful. OP complained about having to do this, but some of the other applicants might have found it difficult. Sounds like it was successful.