Personally I think Seeking has had its day. Their move to a more traditional style “dating” site has changed it completely. They also removed the word “arrangement” from their registered name. Most of the users on both sides are/were looking for an arrangement so why change it?
They now see themselves as some kind of high end dating site which is utter bollocks. They got greedy and milked the cash cow dry and now the proverbial bird has flown the nest.
Agreed, it's still good, not great, seen better days, it is surprising something's not filled the void. Theres usually multiple decent options for a service, however, with seeking they're still the best option out there, even though they're not trying to be an option anymore.
I don't know the ins and outs, possibly theres issues for sa and any new sites with legislation due to it being a platform used for solicitation. Either way, I don't think the demands gone away, there's just not a good option that's well promoted right now, hence why i'm currently using sa and trying out different things too.