The sad truth is this game does not have the population to support the design of full groups being required to do anything
It does not have mechanics in place to facilitate grouping (such as fast travel or teleporting to your group members).
This combined with other disincentives (such as potentially losing all loot on death and having no way to feasibly retrieve it) results in a game that requires a group, but takes hours to get a group together and the content still may not be achievable / may end in frustration/struggle/bag running/ ragequit.
I've ticked "I play solo" above, but the reality is, I'm happy to join groups doing stuff "outside" - because at least if it all goes sideways, I have some chance of retrieving my stuff, or, if life intervenes and I have to log off, I can get myself back to safety. However in leaving my LFG flag turned on for 8 hours a few weekends ago I received not a single message, nor did I see a single chat advertisement for groups wanting players my level for any outdoor activity.
A lot of older MMOs have faced this problem, with games designed to be 5-man or 6-man activities simply not being able to raise the numbers on a regular basis to make the game fun. And they've compensated by either adding solo friendly content, or adding hirelings, mercenaries, or other things to the game to make the existing content doable with fewer people. I think Embers can absolutely remain a group-based group-encouraged game but increase the viability of other activities for the playerbase for when groups aren't happening. By doing so, you get people online concurrently working on solo stuff (crafts, achievements, side quests, housing, gathering, pet-wrangling, treasure hunting - whatever, make up as many solo activities as required) thus a bigger pool of people to potentially see group stuff happening in the chat and join up. Games that do not adapt end up going by the wayside and none of us want to see that.