I'm an old forum user, I've been using forums for over 20 years, and most of them were about gaming, electronics and hardware/PC forums
Several forums have died, but there are still 3 that are active and I still participate, apart from here of course

Bitcointalk is unique in that sense, no forum I've been on has used a signature campaign system or anything close to it
The ones that are active today certainly wouldn't accept such a system, since they are more "centralized", and the forum owners wouldn't gain anything from it.
The forums are making money from advertising and also from commission links, and on these forums you can't even mention or refer stores that aren't in their commission system, they delete your post and you can be banned

It seems that this system only works well here because of the freedom we have and if you think about it, it works very well here, usually the community helps each other if there are problems, or if a scam appears, with the merits, DTs, trust etc