Why wouldn't she?

For a more serious answer, I think masters (the mobile gaccha game) gave her quite a boost since she was kind of the mascot at launch and spawned some memes. Plus BW2 popularity plays into it. And she's really cute.

As a professional mainline anime hater, I also like how she's untainted by being forced into a pairing with Ash, unlike May, Dawn or Serena.