What Apple is attempting to do is to enable Siri on the local level. A problem Apple has is that without the large external dumping that Google and Microsoft do, Siri is at a disadvantage. Apple is emphasizing data security and privacy, while their competitors are more concerned with the collecting of that data. But that also allows them to enable their voice assistants more effectively.
In addition, by keeping requests in the local device, rather than sending them out to the companies servers, the security is greater, and there is no chance the query will be kept, along with the answer, on these servers, for future data mining, sale, or use for advertising.
These purchases are intended to deflect these advantages of non local queries and data holding.