[josephcsible]

Wasn't there also a hacky way to achieve the same goal as registration-free COM even before it existed?

[p_l]

For in-process DLL-based servers, you could try to implement CoCreateClass (IIRC) manually and bypass GUID-to-server lookup and go directly for loading a DLL and calling the method for getting the object from it.

[pjmlp]

Probably, although I tend to stay away of such solutions, as they eventually turn into headaches to sort out in some machine, where the hack doesn't work as expected.