Running the end result on end-user hardware is well understood in certain domains:
Mobile app developers will use their work on mobile phones and tablets.
Good web developers will test across different browsers and will use the tools to adjust window size to common resolutions. This is really easy to do and well supported by the software.
The bigger problem, IMO, is the trend of having UI/UX designers completely separated from developers. They end up making prototypes that look good in presentations and other abstract formats, which are then handed off to developers to make into something usable. Good designers will use the tools to visualize designs in target resolutions, but often they end up optimizing for what will look best in their portfolio or on a presentation instead.
Running the end result on end-user hardware is well understood in certain domains:
Mobile app developers will use their work on mobile phones and tablets.
Good web developers will test across different browsers and will use the tools to adjust window size to common resolutions. This is really easy to do and well supported by the software.
The bigger problem, IMO, is the trend of having UI/UX designers completely separated from developers. They end up making prototypes that look good in presentations and other abstract formats, which are then handed off to developers to make into something usable. Good designers will use the tools to visualize designs in target resolutions, but often they end up optimizing for what will look best in their portfolio or on a presentation instead.