Sorry but as a UxD of 15+ years, that is exactly what I and my team do. It is entirely possible and reasonable for a little d designer to understand and account for the realtime forces that affect a user in context.

The problem is three-fold. First, is that UxD has become a catch all for any digital designer (it took me 8 months to hire 2 qualified UxDs). Second, most companies simply don't pay for professional design talent.

I can tell you with certainty that banks pay between 30% and 50% of market rate for senior design talent. Most mobile app startups pay slightly less than that.

Third is that we don't write the code. We can only recommend what a developer should build and what a stakeholder should prioritize. I've watched both sandbag good design in favor of more features more times than I can count. I've watched both sandbag good design because there was no percieved business value more than once. I've had so many countless conversations with developers who wouldn't do the work because they didn't know how to implement a design and wouldn't admit their knowledge gap.

A true UxD who can cover interaction, behavioral psychology, kinesiology, aesthetics, workflow, accessibility, information architecture and basic research methods can command good money that most companies outside FAANG aren't willing to spend.