Here they have a way to confirm that what you gave them produced more meaningful plaintext. And considering how large this PDDB might be, you might never be able to give them enough passwords to produce as much meaningful plaintext as could have been stored in it. Therefore they might never be satisfied that you have produced all of the meaningful plaintext plausibly stored in the PDDB.
You might as well say that giving the user plausible deniability also means giving their adversary plausible never-reaching-the-end-of-the-barrel. The former is good for the user if and only if the adversary is willing to pretend the PDDB thing isn't a thing, but why would they?
No, plausible deniability tools are not useful to most users. They are plausibly useful to a class of users (spies?) who might have resources or recourse to leverage that can be used to a) get them set free, b) without much or any torture, and c) without having to reveal their secrets. That class of users must be very small.
I don't think that's a fair conclusion either though. Torture resistance is just one of many security properties someone might care about and for most people it's really not the biggest worry.
The PD aspect might be a lot more useful in a more lawful coercion setting or a setting with more limited coercive access (i.e. a mugger threatening you with a knife on a street - can't afford to torture you for days just in case you're hiding something more).
Here they have a way to confirm that what you gave them produced more meaningful plaintext. And considering how large this PDDB might be, you might never be able to give them enough passwords to produce as much meaningful plaintext as could have been stored in it. Therefore they might never be satisfied that you have produced all of the meaningful plaintext plausibly stored in the PDDB.
You might as well say that giving the user plausible deniability also means giving their adversary plausible never-reaching-the-end-of-the-barrel. The former is good for the user if and only if the adversary is willing to pretend the PDDB thing isn't a thing, but why would they?
No, plausible deniability tools are not useful to most users. They are plausibly useful to a class of users (spies?) who might have resources or recourse to leverage that can be used to a) get them set free, b) without much or any torture, and c) without having to reveal their secrets. That class of users must be very small.