All the fora you mention are characterized by lack of longform text. What people are creating today tends to be image-heavy and eschew any long argumentation or prose storytelling.

Having just a smartphone obviously represents a limitation. For example, I am a member of some niche travel communities. A decade ago, when it was common for people to lug a laptop, there was a healthier community of people writing detailed blog posts on certain destinations, editing Wikivoyage or Hitchwiki, etc. Now that those same travelers are leaving the laptop at home and traveling only with a phone where it is inconvenient to enter much text, the ecosystem of travel resources is actually poorer than it was in the past.