She’s not objectively busted, everything says otherwise. At best, she’s middle of the pack, at worst she’s actually pretty subpar.
You, again, need to stop conflating “I don’t like her” with “She’s boosted and broken!!!” When even stats say otherwise, I would think this would inspire something in you to just accept you don’t like her for personal reasons, which is fine. Your exaggerations discredit you far more than they justify you.
If it doesn’t translate to a win, where is she boosting to? At least in the ranks I play, you’re likely not going to boost, let alone on Mercy, when there is a Juno. Which is the whole point. Juno is doing everything better than other supports right now. If you rank Mercy above her, that would be a big yikes and a self-tell.