Firstly, since Google/Facebook/miscellaneous mega-startups, there have been people with enormous wealth and power who got there through the 'engineering track', and love developing software, even if they don't do much of it any more. There are nurses who find their jobs intensely rewarding, but CEOs of big medical companies are not typically drawn from their ranks. So there are evangelists for code with powerful public platforms for their statements.

Secondly, the smarter of the SJWs realise that - in terms of diversity and so on - there's a supply shortage further down the pipe. So a disproportionate number of do-gooder startups/tech non profits are focused on teaching more kids from different backgrounds the basics at an earlier age, since that is a sincere concern among the people who found such enterprises. (Throwing money at such things is a cheap, convenient PR move for the likes of Google, as well.)

Thirdly, as others have pointed out, teaching somebody to code requires a light capital investment up-front, relative to the value of the skill. There's no way to become a doctor without years of med school; you can start throwing code around as soon as somebody gives you a refitted chromebook and tells you to type "print 'hello world'".

Fourthly, hype around the Valley and the tech industry today.