With modern 3d solid modelling software, a working model of the finished product exists in 3d space.
The model may be spun to show different views, parts can be hidden to see inside, behind, under, over etc.
The model may be animated to show the way in which different parts interact. Views of the model can be inserted into presentations.
It is possible to see the finished product working.
This promotes understanding and allows meaningful presentations to be created to non-technical staff and/or as an aid to sales and marketing.
In addition, assembly and service staff can have animated assembly instructions available to them during assembly and/or when carrying out service and repair on site.