it is true that the group of respondents were mainly foreign players playing solo.
from my observations on a group of 1,476 people. It turns out that interlude servers have a longer lifespan for solo players due to the visible end game, compared to H5 where there are a lot of new att solutions, certificates, bars, etc. a lot of weapon sets.
in a group of 276 players playing on "e-global", most people left the server due to problems with leveling, the group argued that there were a lot of instances that took up game time but did not give proportionally more experience compared to the previous stages.
To sum up, the main problem of solo players is the time they have to devote to the game, above level 78 reaching one level in the instances is almost a miracle, if we skip the instances we are not able to get dressed, we are not able to level up by going to the instances.