I don't think things like AdFly should be outright taken down. But I do think that it should be banned from specific sites. Especially ones with a lot of younger people as the audience. Personally, I've never seen any inappropriate ads from AdFly, but I've seen a whole lot of fake downloads, designed specifically to trick people who don't know better. And considering a lot of these contain malware too.
I'm really not sure what AdFly could do about this, which is likely why they haven't fixed the problem entirely, but they have been trying, I think. But at least for now, It think the only thing that should be done is the banning of AdFly on sites with a younger audience.
Unfortunately, I don't think that will be happening, but still.
Of course, this is all just my take. I'm definitely no professional on the matter.