"More trouble for less response is not encouraging."
Depends?
I would rather have 1 considered response than 200 likes.
I am also happy to wait a few hours for a reply, I don't need the instant gratification that social media delivers and then gets you addicted to.
I nearly always get considered responses in FB. The same number or more than I used to get over here. Also, people use my uploads as springboards for their own chatter, so I feel the discussion evolves somewhere, even if offtopic.
There are quite considered discussions on FB too, although they go on for a shorter time and are not archived as effectively as on fora. On the other hand, the FB searches work whereas the W-E searches don't work. I cannot find many archived discussions here even if I remember them and know they exist somewhere. (I do save interesting FB topics and create my own archive. FB has a tool for this. No doubt a tool that is used to sell me stuff related to my interests...)
Most responses on a forum tend to be just likes, but since many fora don't allow likes, people need to write a message. I don't see most one-liners or thumbs-up emoticons anything more than a like. I certainly know most of my messages on this forum are just thumbs-ups and chatter, the equivalent of FB LIKES. Thus in my experience there isn't more considered discussion on the fora, AND the barrier of liking is higher than on FB.
I admit I like the gratification. It doesn't have to be within an hour, but if on a forum there are just two one-liner comments in a day or two, I much more prefer 30 thumbs-ups and three considered replies on FB.
Perhaps most importantly, the FB groups where I'm active have people who tackle similar projects to mine, AND people I know personally and play with. This W-E forum has seen less and less Empire hobby, and these international fora lack the personal aspect. I guess the EEFL forum actually has an active nucleus of people whose hobby happens in the Old World and who know each other and play together. Close topical connection and personal friendship are big factors.
Then there is the reality that this site started to lose impetus during the late 8th ed, and contracted drastically since 2015. It's a shadow of what it used to be. The memory of old shadows my enjoyment of what is and can be achieved now. A kind of Noldor syndrome, I guess.

As new platforms with new people, the FB sites do not have that burden - and they are much more active.
-Z