Well you can, it just takes the extra step of grabbing the download from the page. I have done it before but I dismissively misspoke and should have said full index of subtitles available.
But can you -- without paying? AFAICS, only if there are fewer items in that full metadata list than the number of pages you can download for free. And the impression I got from this discussion was that this is definitely not the case.
If you don't pay, they'll limit you to 5 downloads per 24 hours. If you pay for a "VIP" account you can download 1000 subtitles per 24 hours.
How long would it take for you download all 6.260.893 subtitles listed in the "dump" with these limits in place?