Blitz has a 1.0 AP ratio on both his pull and ult, along with another .2 on his ult's passive. grab a lich bane for his E, and you have respectable damage. If you want to go AD, he has a strong AS steroid, an AA reset with bonus damage off of AD, and a pull. Also respectable.
soraka mid can be quite annoying. Sure she can't heal herself the same way she used to, but if her Qs keep landing, she will harass you out of lane while keeping healed. Along with a silence/snare, she is quite helpful to jungle ganks. A solid pick of played right. Just because something is a "support" champ, doesn't mean that they can't do other things.
Nidalee was a "support" champ for a long time, until people figured out her spears did insane damage when AP was built, and then she became a mid laner. And then you know the rest of her history from there.
Alistar was an OP top laner for a few patches when people figured out you could proc sheen after a headbutt. Still a support, solo laning like a champ, and being hell to lane against in that.
Supports are put in that role because they have CC that can be used to get carries fed. There is nothing in that that says they are weak or vulnerable, or incapable of solo laning.
Just because someone is taking a champion outside of the place where it seems they make sense, doesn't mean that they're trolling. It can just mean that they have an alternate and unexpected strategy to abuse.