Same way you get strong in an age of heavy machinery: Lift heavy weights yourself.

Skills will have to be built through artificial constraints. Pen & paper, reading books, not using AI, etc.

this 100%. Skills are gained via effort. Not too much effort that it discourages you, but enough so it's a challenge and engages you. Ofc it helps to have wonderful teachers, coaches, mentors, books, even ai to help guide you, but YOU must put in the effort. You don't get something for nothing.