Speaking only for myself, my activity in the Forum (both posting and reading) has been severely impacted by use of chat apps (Line, Discord, etc.)
When I started playing a year ago, I found the Forum pretty quickly. Having utilized resources such as GameFAQS, Brady & Prima Guides, etc. when playing computer and console games over the years, the Forum was a natural place for me.
As I became more serious about the game and joined more competitive alliances, I was encouraged and/or required to install the chat apps for improved alliance communication.
Because so much game-related business is conducted via the apps (strategy, recruiting, coordinating mercs, and just chittychat), the volume of messages there means I can only check the forums briefly and occasionally now.