If social media activism actually worked, wouldn’t the world be fixed by now?

Every other post I see on social media (especially this platform) seems to be related to some serious cause, and calling for action or change. And yet it seems to be the most ineffective form of protest imaginable.

Can someone explain to me what brings people to constantly obsess over political stuff online rather than taking action in the real world? Is it just to make people feel like they're making a difference?