I advise training programmers instead of throwing them in front of a screen without any training. Companies these days provides no training at all. When I was hired over 40 years ago, I spent plenty of time being trained for my first 3 months. Now, nothing, and you if you want to train a new person, you do it on your own time.
I wonder of part of the issue is that 40 years ago, people typically stayed much longer with companies. (I actually don't know what the norm was. My dad was an EE for the defense industry, and IIRC he worked for 3 different employers over his career.)
My dad is in his 60s, started his company with some friends in the 90s. None of them got super rich, but they are all doing well, and all slowly going into pension. The company grew to a mid-size level, but actually most of the early employees stayed, and I think the average tenure is still probably > 10 years. Switching jobs every 3 years is weird, it is pretty much the time it takes to learn the ins and outs deeply enough to be an expert. There's some sense to it, as after learning all you can, it might be better for your career to search for new challenges. There's also the nonsense that switching that often generally yields significantly higher pay.