I wonder if you realize that in many countries, computer science was a very obscure academic path until very recently. Most schools in France wouldn't offer it until very late for example.

The older, more experienced people at these companies you cite are the ones less likely to have CS degrees, which only became a staple recently. The companies now ask for one because it's an easy mass fizzbuzz filter. It doesn't help them get the best engineers, it helps them not get the worst ones. They have the volume to make up for it.

Saying what they're doing shows ignorance as to why it's working.

Sure, there may be a correlation between a candidate's ability to answer every kind of algorithm & data structure problem across multiple respected CS textbooks and their performance at any one of these companies, but what of the many other confounding variables? What of the benefits, day-to-day perks, prestige, future open doors, workplace culture, or scale of the products they launch? Do those kinds of variables not also greatly impact the ability to attract and select top talent?