Not only that, she is the only support who cannot defend herself, Sona, Janna, Lulu, Braum , etc all have something to defend themselves with and run away, but raka has slow base movement speed and no escapes or reliable cc.
Well thats just not true. Soraka can beat most of the supports that are not damage focused 1v1, since in a battle where both sides have low damage, the constant slow from Q + selfheal wins. (I am assuming that you put a few points in Q first, since i think thats most reasonable if you want to be usefull)
You can escape with Q+E (btw you should never throw away your E as single spell unless you absolutely have to or just want to stop a channeled spell always chain it with your Q or allied spells) and you then cast out of range Q's that your pursuers run into. There are very few champions that have enough mobility to catch up with that. Despite her slow base movement speed Soraka is actually very good at kiting.
So even the enemies with the highest damage would slowly die if you play correctly. Soraka doesn't have a lot of potential to chase down kills herself, but if she is getting chased she can deal quite a lot of damage while being relatively safe.
About breaking the meta, there are some very easy match ups, especially melee assassins or more squishy melee fighters like Riven.
But Sorakas main weaknesses are :
- her lack of abilities to get cs under tower,
- her low AD coupled with extremely slow traveling bananas make last hitting very hard
You can't consistently carry many games with a "mage approach", you often
- have to transition into some kind of support to be efficient and thats kinda tricky to be support while being assigned to a solo lane.
If you are constantly getting pushed in you would
- rely on your team to have any chance of breaking out and having a chance to make an impact.
Other champions get tons of damage as the game progresses and become a lot more threating to you and you simply cannot face them anymore at some point. The heal over time from Q that was strong in laning phase just wont be enough anymore so you would end up ulting in an attempt to 1v1 somebody and that on its own is a waste and probably won't be enough either.
I don't even care that Soraka isn't truly viable as support, I think it's totally OK that she is pure support. However many players don't know how to handle a solo lane Soraka, so you kinda have the surprise effect on your side should you play it.
At any rate you might be right that she is sub-optimal as solo laner but definitely not for the reasons you mentioned at first.
Your options are winning early or becoming a strong support or both. ;D
Carrying late game with Starcalls is unlikey to happen....very.
So long...