While I know GitHub does that (see, e.g., https://github.com/kragen/stl3dpy/blob/master/showerring.stl) I think it's lacking a lot of things to be a reasonable Thingiverse replacement. It can render STL files, but not OpenSCAD or STEP/IGES, for example, and it has no way of associating different files (even files it can't render) to a single "thing" the way Thingiverse does. From GitHub's point of view, your example is a random file that belongs to a project named "3D", and mine is a random file that belongs to a project named "stl3dpy". This poses obvious problems for implementing search.