The discord thing evolved from when groups started becoming forum only, (sited) or where you had to report your status in trainings and such, eventually people would just do 1v1 rp's over the forum, then Skype.. now discord. I remember, briefly before the update, when people were blaming private maps for the downturn in rp, too.
It has nothing to do with the maps. If it did, those maps wouldn't be empty, as they are readily available here on the forum. It's that those in that original community have for the most part moved on. To a different platform or just in life. I, personally didn't even know what rp was until I was able to join a group and watch them rp until I felt comfortable enough to join in.
The big local-channel rp groups are for the most part gone. The benevolent clan was the last big group to outlast the change over after the great Thanksgiving hack of years ago. For many of those members, the login was just too much to deal with, or it gave them the excuse they needed to move on. Whichever the case may be, it's the members you miss, not the maps.
That said, I'm in agreement that discord only rp defeats the purpose of getting on fh.