It kind of has, although I would argue that Siri is more successful than Cortana.

If I recall correctly, the thing that made Cortana particularly frustrating and worthless is that it did all searches using Bing, and opened any websites using Edge, regardless of your default settings. You got forced to use all the Microsoft version of every tool, even if you didn't want to.

I get the impression that it is, at least to some degree