Rihanna is the most streamed artist in 2015 on Spotify with no album

[Didymus 34,380]

I mean, it wouldn't be impressive if her streams were significantly lower than the leading male artist. But that's not exactly the case, she can keep up, which disproves all the "she had no competition" arguments.

For the people who don't wanna go back to the OP to find it:

Most Streamed Male Artist = Drake (1.80)
Most Streamed Female Artist = Rihanna (1.57)

So in this case, exactly because she had no female competition, I think it's actually wiser to compare her to male artists in terms of streaming. The idea that she has to compete only with females in streams is ridiculous anyway.