Certainly no confirmed method, but CMDRs *have* been using theories (mentioned in this thread) that have been somewhat holding true to narrow down the search. Combined with the SC lag to narrow down the sites on a candidate planet, it is by no means brute forcing. Following this thread closely I believe that they've certainly had enough time to find the other sites legitimately (the last few were found *today*, not "rapidly" since the Galnet article). Those who think that the SC trick isn't legitimate need not reply. I'm aware of your arguments and do not apply to this situation. By legitimate, I meant without the use of external tools, things that would violate the EULA like datamining assets and memory scanners.
Given the amount of time these few explorers have been putting into searching for the rest of us, I don't believe they deserve the these kind of insinuations.
There's certainly a lot of ruins to find (hundreds!) in an area of space the size of the Bubble. So by no means feel left out, you can go out and still find new ruins as no one has found all of the solo codex entries.