That the ideas are given little attention is the substantial basis in determining that they are fringe.

If an idea is given a lot of attention, it might be mainstream or fringe, depending on how accepted it is. It might be getting a lot of negative attention, or it might just be getting a lot of attention right now. It might be transitioning from fringe to mainstream.

But if it is not getting any attention, or very little, then it is by definition fringe.