The interesting thing is how well accepted this is. Go on Reddit's /r/cscareerquestions (a popular forum for programming job help) and you'd get downvoted by people who prefer to have to "study" for the test.
Source: I work for one of those companies.
The career progression for me and a lot of my friends who were high achieving students was to start out at one of those companies. A lot of us didn't have much money saved up, and didn't come from much money. After building up some money, and realizing the little surface area to work with at one of these companies, we left.
Visa issues are also a very real problem that chain a lot of good talent to these corporate juggernauts.
It's sort of the same argument people use for justifying ranking AI X-risk as the highest concern for Effective Altruism.