They probably have a bunch of data and are trying to guide people to whatever they're convinced will get people to break down and give them money for. I have no idea about the demographics here but I imagine that if there's a ton of women reading that they'll tailor their promotions to what women want to read. The fact that Webnovel has a relatively large amount of male-centric novels is quite interesting considering how Wattpad feels like a "NO BOYS ALLOWED" zone to me.
And on a related note Wattpad introduced an equivalent to Spirit Stones, called Wattcoins, though I have no idea if they function under the same pay-as-you-read model or if they want you to buy complete works all at once.