Of course not, the premium method is available not just for social media applications. It applies to messaging applications as well. There are a lot of people who use applications like Telegram, and Whatsapp for sensual video chats amounting to a payment.  However, it must be considered that social media applications are more discreet and have better features for operating a private channel for any kind of content and this is why Snapchat has more popularity in this context.