The only counter play is to focus her, but she gets a shit ton of MS from her passive,
Oh yes, she has an on-demand escape. It's not like she can only do that when there's a low health ally she's moving toward.
and she has self peel with her E.
God forbid a support have any tools to protect themselves. Especially "self peel" that you can walk out of that doesn't even slow you down unless you stand on it for the whole duration.
She is EXTEREMLY annoying to play against when you are playing a melee because if you are in her E as a melee carry,
You know what kind of cc is stronger than silence? Stuns. Can you walk out of a stun? No... well, not when you're stunned (inb4 smartass Ekko remarks :P )
or can carry her entire team by healing everything she sees on a 2 sec cooldown.
She can only heal one person at a time with that cooldown, her ult has a decent cooldown, and it costs her own health. Unless it's late-game, you fed her, and she has randuin's and Warmogs, you should have some aoe in teamfights or assassinate her when the moment arrives. She can't cast heal forever without her ultimate, and she should be sufficiently squishy.
She heals a lot, we get it. She's the healer. That's like complaining about assassins assassinating (within reason, mind you), tanks tanking, bruisers bruising, marksmans manning, mages maging, and supports buying wards.