Because ADCs think that support is their bitch, which isn't the case.
Support is just there to help you get started since most adcs suck badly early game, and them getting ahead has a very big impact on a game.
Just ignore them, I usually mute ADCs that act like I should praise them, hell I would take kills and CS from them to spite them. Not everything is about the ADC which is an unknown concept to them.
What I would do is do what you want to do, but also take into consideration what the team needs/what the enemy has. Like if they have a Blitzcrank, it may not be a good idea to play Soraka or Sona even if you want to since if you lose lane, its very likely you will get blamed and to be honest, it probably was your fault too, either because you got grabbed, or they got grabbed and you had nothing to stop them like a CC champ would. But if you are good at those champs where you are confident at the matchup, go at it, just better be ready to prove you can not be a hinderance.