Look at it this way: they would try to create a competitive advantage, as they are also behind Wikipedia they could better use it, in the process they can create an API to access information in such a way that other search engines cant.
A better proposal would be to create a project to start adding semantics to the Wikipedia project, maybe a RFC and standards so all search engines can benefit of it.
Another option could be an open sourced project to host blogs making use of the above described tech.
Then you could perform a search based on the "intended meaning" instead of the words included and who reference it.
Edit: Removed Yandex per comment below after research.
I stand corrected, I erronously implied that the fact DDG uses its results implied the same policy about privacy which does not.
"
2.3. Data collected by or transmitted to Yandex, the Company or Partners, in the course of accessing, interaction and operation of the Site and provision of the Services may include, without limitation, the following Data: (i) Internet Protocol (IP) address and location; (ii) cookie information; (iii) browser identification information; (iv) information on your software and hardware; (v) date and time of accessing the Site and the Services; (vi) information of third parties websites referred the Site or the Services; (vii) information related to your activity in the course of the Services use, including, without limitation, search queries history, search results provided to you in response to your query, web pages you visited by reference from the search results; (viii) other information."
Neither of those search engines are even remotely equivalent to a free, nonprofit-managed engine that doesn't track users and provides Free source code and documentation to operate a clone of the index.
A better proposal would be to create a project to start adding semantics to the Wikipedia project, maybe a RFC and standards so all search engines can benefit of it.
Another option could be an open sourced project to host blogs making use of the above described tech.
Then you could perform a search based on the "intended meaning" instead of the words included and who reference it.
Edit: Removed Yandex per comment below after research.