What I think?
Supports, specifically caster supports (Soraka, Janna, Lulu, Sona) are in an impossible position.
Why? They do not do well with or against ADCs, but the meta and Riot enforcing the meta forces them to stay there.
Think about it. What do ADCs have in terms of kit strengths? They all have lots of DPS, sustain through lifesteal, and most have harass. How do you beat that? What attributes are ADCs missing that would help them kill things better? The answer to both of those questions is CC and burst. Most caster supports either don't get hard CC until 6 OR their hard CC is almost impossible to use to start a fight. Also most of them don't have spectacular burst because they have at least one spell that does zero damage. Nami being the one exception and surprise surprise she's doing the best of the caster supports.
So what happens when people use supports out of bot lane, where they can actually take advantage of the parts of their kits that are kinda meh in bot lane? Well, the playerbase generally start complaining about how 'toxic' it is and then Riot either nerfs them (Lulu and Old Soraka) or reworks them so they lose a TON of power without a lane partner (Sona and new Soraka), both of which feel horrible.