Well, not 100% true. For example, if a game has tracks which can physically be written back on an amiga drive, then you could use mfm2wwarp/wwarp (from whdload page) to write the disk back.
Of course, I'm not sure how many games fit that category. Not many I would think. You can write Rob Northern tracks with Wwarp if you have the SYBIL hardware (but who does?).
Something like Shadow of the Beast 1, you can write back all but the "protection" track.
I just tested with Bart vs the Space mutants, and was able to write the first disk back ok for example.