I'd continue to compare it with how free software appeared. It was barely feasible back then (end of 60th - begin of 70th) to work on software at home on a PC, since there was no PC. Still the software could already be open/free and exchanged between big enough players with big computers. Only later the things changed. But even now there is free software which is nightmare to program on a usual single PC.

Thus it is either to early to define "open" for AI. Or "open" must be truly open. Though it remains not practically achievable at home or even at small companies.