If other girls released as many albums as Riri released in last couple of years (since Spotify launched), they could've been #1 too.
Having more material out is an advantage in this, and if most of the material is recent, thats even a bigger advantage.
Gaga
Most of her work wasn't put on spotify till months after it's release. and we'll never know if it's an advantage till another artists starts doing it and benefiting from it. But try on
when Love The Way You Lie PART 2 has over 25.000.000 streams... WTF are you pressed about?
Did you even had any doubts that Rihanna is the most streamed female in the world? She even was the most streamed female this past year... and she didnt release any new albums...
She has 4 songs above 100.000.000 streams... and she is over 1.000.000.000 streams all together.
I'm loving the pressed vibe I'm getting in this thread. Rih still has it 
at the Queen resting comfortably atop the streaming charts.