Specifically, heretofore, I had assumed that the key to finding fellow players who could write well on a social network service was to find the correct social network service, given an arbitrary gaming title.
Wrong.
Apparently, the key was to find a gaming title with users having the correct level of literacy, as opposed to finding a social network service for an arbitrary gaming title.
It seems that different gaming titles attract players with widely disparate levels of literacy, even for the same social network service.
Specifically, after failing with my original tactic for 8 years, I eventually gave up and decided to compare the level of maturity for differing gaming titles on Discord, which I had previously avoided, assuming that all servers on that social network service would share a similar level of semi-illiterate users.
To my surprise, the level of literacy differed greatly depending on the specific gaming title, even though all servers visited were on Discord. Discord servers for certain gaming titles were substantially populated by players who wrote using semi-illiterate English (sentence fragments, Internet slang, grammatically incorrect English, incorrect spellings, vulgar English, etc.), whereas servers for other titles were chiefly populated by players who apparently knew how to write at least semi-decently.
The most mature players seemed to exist on the server devoted to "EverQuest II."
Another server with relatively mature players was devoted to "Lord of the Rings Online."
However, "Elder Scrolls Online," to my surprise, seemed to feature mostly players who did not use full sentences or grammatically correct English.
Overall, among the servers that I investigated, the ranking for player maturity, as evidenced by writing style, was as follows (servers with more mature players are ranked higher):
"EverQuest II"
"Lord of the Rings Online"
"Secret World Legends"
"Final Fantasy XI"
"Final Fantasy XIV"
"Elder Scrolls Online"
Disappointingly, generally speaking, at least in my opinion, there seemed to be an inverse correlation between the degree that a given gaming title was interesting to play, and the degree that its players were mature.
I.e., overall, more interesting gaming titles seemed to attract players who were less mature.
Personally, I enjoy playing "Elder Scrolls Online" much more than "EverQuest II."
However, I enjoy chatting with fellow players in "EverQuest II" much more than in "Elder Scrolls Online."
This phenomenon raises a rather curious question: How can I chat with mature players who write well in a gaming title that is fun to play?
Apparently, boring titles attract interesting players, and interesting titles attract rude, immature players who cannot write well.
Alas.