The forums are for many different purposes including suggesting ideas, getting help, and even advertising your projects!
Makes sense. It's easier to get known in the forums. In the entire scratch community, your projects are just a small fish in a big pond.
That's why you get more followers here.
For me, it's the latter 25% followers.
People knows you when you answer their questions. If they appreciate your answers, they follows you.
Thanks so much for the replies, everyone! The forums are a lot more chill than the main site - you have a far higher chance of getting a mild to moderate following off helping people and being an active person on the forums. The main site, due to it's far higher usage could possibly give you a super spicy ghost pepper following, but more than likely you'll just be left with water
I do agree that the forums are a lot more lax than the regular website (for one thing, you can post images and posts up to 200000 chars).
In terms of advertising, I'm not a big fan of it and I only do it on my profile. I know what you mean when you say that projects are just fish in a pond, and because everyone sees your posts but not everyone sees your projects, it makes sense.