Sorry, Cortana no speaka Chrome, Firefox, Vivaldi, Google, DuckDuckGo…or anything but Edge and Bing.
Microsoft's reason for doing so is that the changing of the search provider and browser supposedly compromises the search experience on the operating system.
“Unfortunately, as Windows 10 has grown in adoption and usage, we have seen some software programs circumvent the design of Windows 10 and redirect you to search providers that were not designed to work with Cortana.
The result is a compromised experience that is less reliable and predictable. The continuity of these types of task completion scenarios is disrupted if Cortana can’t depend on Bing as the search provider and Microsoft Edge as the browser.
The only way we can confidently deliver this personalized, end-to-end search experience is through the integration of Cortana, Microsoft Edge and Bing – all designed to do more for you.” – MS
Windows 10 users are to be limited to using Bing and Microsoft Edge when using Cortana's web search functionality.
And we all are supposed to believe that “We’re doing this for you” nonsense? Seriously? Where are my waders?
Ummm…tell me if this is more compatible with the truth: Those using Cortana will be now Edge-Bing users. MS will sell more ads on Bing. MS will make lots more money, like Google.
Well…starting to understand why W10 is free (for now)? It’s a good OS, but it’s a gateway into all things MS…sort of like the drug dealer business model: The first few fixes are free…but after that…oh yes...and "All your browsing data is belong to us." But don't worry. It's "anonymized".
Source:
http://www.ghacks.net/2016/04/29/microsoft-blocks-search-engines-windows-10/