Companies discontinue products all the time due to acquisitions, bankruptcy, restructuring or simply re-orienting investment and I've never seen them held to this standard of having to host it somewhere external. I'm not even really sure how that would work.
A commenter here shared an example of a similar product shut down by Microsoft: https://en.wikipedia.org/wiki/Remix_3D
Disclaimer: Googler, but in no way connect to the Poly team.
Edit: Added Remix 3D example.