I am going to try to justify the Sona nerfs
braces self for downvotes
I think the Sona nerfs were because Sona was very strong for a long time. Riot says that they're being careful with the OP champions like Ezreal before nerfing him. I think it was the same with Sona. I think Riot was being careful with her for a long time before nerfing her, and I think they're going to do the same with Ezreal and the like.
But I'm level 14, what do I know