That’s not the claim in the OP.
OP said that if hide-and-rez was fixed, then it should show up in global healing stats for Mercy. It don’t show up, so it means that either hide-and-rez was not as universal as people think, or it was not fixed and Mercy still lose too much healing time using current rez.
Other people started talking about how she was dominant, underpowered, or “meta”, now or in the past. And those arguments bear no correlation with the claim OP is making.