You nailed it. In my opinion, in this industry, it is much natural to start as a discretionary trader and then learn to write code and find your balance between a discretionary and systematic approach, as opposed to start as a programmer and learn how to trade.
The thing is that in trading, you learn a fantastic amount of things in regard with the subtle nuances of the markets when you trade manually/discretionary. So I would say that one of the big issue of the newcomers, is their lack of understanding some mechanisms behind the scene and jump straight to coding.
Full disclosure: very likely I'm biased on this given that I started as a trader and then learned how to code
