They closed other sources such as websites, and VPS hosting mirrors. You cannot simply "close" WhatsApp or Telegram or SMS, that is not how it works, unless you just cut the service for everybody, or go down the rabbit hole of chasing hundreds if ad-hoc groups.
Still, the real victims here are the 50%+ of Spaniards who want to remain being Spaniards. In my opinion, while there are people who want to continue being part of Spain, the government is doing right protecting the law and shutting the secessionists down.