Could this be an advantage that Google can use to train their models on but others won't have access?
Google wants it to be more difficult to notice rewrites? Journalists to often have found valuable information with it?
Unrelated: Google should probably think about a sizable donation to the Internet archive.
Maybe - I guess that they must have served that "cached" content from DB-records that had it all saved directly (URL X has contents Y => basically a "mirror" of the terms that they indexed) => not having to store that "mirror" (only the search index) might save quite a lot of storage space (and I/O and CPU to decompress it, as users won't be requesting it anymore) => all in all that might save quite a lot of infrastructure costs $$$.
> Could this be an advantage that Google can use to train their models on but others won't have access?
Maybe (if they decided to just get rid of the I/O related to the user requests), but on the other hand I don't know if previously any "Google-consumer" was ever able to perform mass-downloads of Google's "cached" data - could that be done without being banned by Google's webpage (or API)?
Google obviously hasn't cared about that for a long time.