[PeterisP]

That's not sufficient - the "private" knowledge graphs of e.g. Google aren't "crawlable", they aren't public and don't (solely) rely on the sites. DBPedia+Wikidata+all other open data sources are not sufficient for a good knowledge graph that can be competitive (in terms of coverage, thoroughness, and recency of updates) with what the megacorps can afford to maintain behind closed doors.