So, you have Onshape, the browser-based 3D software to rival SolidWorks, Solid Edge and Inventor, and you have Frame, the browser-based platform where you can run SolidWorks, Solid Edge or Inventor in the browser and from any device.
Why would you use Onshape when there is Frame?
Why would I need a mobile app version for any of my software, now that I can run SolidWorks or Photoshop from any device or location?
To me, it comes down to features and accessibility, compatibility with other software and not being locked into one format or the other. If Onshape has the flexibility that logging into Frame and starting up various software doesn’t, it’s a winner. Beyond that, I’ve not heard a convincing argument for using or developing browser-based/cloud versions.