I am not sure these publications were intended to generate sales of these technologies. My assumption is that they mostly help the company in terms of recruitment. This lets potential employees see cool stuff Google is doing, and see them as an industry leader.
Spanner is literally a Google cloud product you can buy ignoring that it underpins a good amount of Google tech internally. The same is true of other stuff. Dismissing it as a recruitment tool indicates you haven’t worked at Google or really know much about their product lines.
Spanner research paper was in 2012. Bigtable was in 2006. GFS 2003. The last decade has been a 'lost decade' of google. Not much innovation to be honest.
