Per user keys are also very useful for use cases like a personal file storage service, even if traditional RDBMS don’t work well with them. Techniques are situationally dependent.
I was not being dismissive of the existence of technical challenges, but rather dismissive of comments like:
> To be honest, in the age of modern overprovisioned storage drives that remap blocks frequently, I'm not really sure you can implement genuine "hard" deletes without choosing significantly unorthodox hardware (or destroying a drive every time you need a single bit erased), no matter how much you want to in software.
Which seem to completely deride the possibility of compliance.
Compliance is feasible, even if it has challenges.