No technical reasons for it, just manufacturers seemingly not understanding that there are plenty of content creators who also like to game.
Or they do understand, but would rather have customers buy separate screens for separate use cases. Why do you think we have 'gaming' monitors now? We used to just have monitors, and a segment for professional work. And among normal monitors you'd also find some high refresh rate models, however rare.
Moar $$$, and less risk as well because you're targeting price-effective products at specific situations rather than trying to do it all in one product. Everything costs money to make.
Specifically for monitors, a big one is calibration and minimizing deltaE color/grayscale devations, a correct gamma curve etc. Gamers don't need that at all. Content creation does. And that's also where the two use cases are at odds with one another: for VA, for example, gaming calibration would nudge towards faster transitions G2G in the lower end of the brightness spectrum (the slowest transitions for VA), while it doesn't help color accuracy.
