Hi Asaf,
Yes, I agree — of course there is some splitting. But I don’t think that creating mockups right away takes me much longer than hi-fi wireframing took me.
At the startup I had to build a design system from scratch and focus in many UI aspects. However, when this was ready, most of my work was UX-focused (+research +some prototyping) and playing around with the system I had already fixed for us.
At WeWork, we also have design systems that help me out and 85% of my work is research and UX. I believe the mature places in the industry find value on Product Designers that are stronger in UX, it’s just that there not many of us just yet :)