Certainly, but it moves it from a "we just have some legally-should-be inactionable data laying around" to "we don't even have that data laying around".
The fact that it's impossible to comply with "who wrote -this- review" is probably sufficient, but "and we don't even readily have access to who wrote -a- review" can help prevent fishing expeditions, since presumably a judge will be less amenable to such fishing expeditions if you can show it will have negative material effect to comply, while still not providing any legal path forward to sue for the prosecution.
But that also makes assumptions both of user counts, and rounds of hashing. 50 million users (seems reasonable with Glassdoor), with a sufficiently slow hash that takes a second to compute (easily done) means you'll have to wait a year and a half for results for a given company, or start to parallelize things, and, oh, look, now you have dev time and CPU resources and, well, this has a materially adverse effect on our business, and we'll be left with usernames we still can't release since this discovery order only is valid for this -one- review, and we have no way of knowing which it is.
The fact that it's impossible to comply with "who wrote -this- review" is probably sufficient, but "and we don't even readily have access to who wrote -a- review" can help prevent fishing expeditions, since presumably a judge will be less amenable to such fishing expeditions if you can show it will have negative material effect to comply, while still not providing any legal path forward to sue for the prosecution.
But that also makes assumptions both of user counts, and rounds of hashing. 50 million users (seems reasonable with Glassdoor), with a sufficiently slow hash that takes a second to compute (easily done) means you'll have to wait a year and a half for results for a given company, or start to parallelize things, and, oh, look, now you have dev time and CPU resources and, well, this has a materially adverse effect on our business, and we'll be left with usernames we still can't release since this discovery order only is valid for this -one- review, and we have no way of knowing which it is.