You underestimate the value of having a different perspective. Yes, it can be a bad move if she is a disaster at coding. But think about what value for the comp

You underestimate the value of having a different perspective. Yes, it can be a bad move if she is a disaster at coding. But think about what value for the company it is to have a developer who has a clue about design and can communicate way above average. How much of our developer job is really about coding? It is a risky move and not one I would recommend to anyone - but it is one I‘ve done myself (incl. pay cut) to get the experience to boost my career. Also keep in mind that careers span decades and while specialization is sought the landscape does shift (sometimes quickly) and diversity of skills can provide a degree of robustness. And yes, the career track slides are not a foundation on which to base decisions.