Architects would use it originally and to a small extent professional engineers because they wanted to communicate in 3d and tools at the time were so bad. It just couldnt do the drawings.

The big problem for architects is it never got to be able to do architectural drawings while other software came in with easier 3d modelling and visualisation (revit which autodesk bought and built out fully for industry use, rhino etc. Even blender).

Google did very little with it and Trimble too. Google i can understand ignoring it after Google earth stopped being a focus. Trimble I dont really understand what they want it for

Also it was notable for being a major commercial success for the ruby programming language, outside ruby on rails.