I am playing on Argo. And I dont think Argo is dying. People just dont post LFMs.
I solo 80 % of the time. Why? I dont know. I guess its just more enjoyable for me. If I want I can get all optionals and breakables and conquest or just invis zerg through and as a small bonus I can go afk whenever I want. If you state doing all optionals in your LFM...heck you always find one of these five strangers who joined that will be whining why we just dont go stright to the end fight or will die far behind you (if you write zerg).
When I am in good mood and see LFM of the quest I am not able to complete by myself I just join. If I dont see any I ll just post one and it fill up pretty quickly (few days ago I posted LFM for elite Dreaming dark at level and we were full in less then five mins).