This is the second time where she got harshly nerfed during the Beta season. One of reasons the why there is such an outcry seems to be that the harsh nerf came so fast. You can say the same about Moira but Moira was already seeing more play time compared to Sym just because of her status as a healing support. She was never in the pits of usage compared to Sym.
Sigma was also just released, so the supposed ‘double shield’ meta isn’t even a thing yet, it’s just people trying him out. (Should I even bring up the fact that harshly nerfing one of the best hero against that supposed meta doesn’t even make a lick of sense).
It doesn’t help that the nerf happened during the role Q beta season, AGAIN, when stuff hasn’t even had the chance to settle. This is basically the same harsh nerf she got during the beta portion of Overwatch 1.0 where she got a harsh nerf hammer before the actual game even went live.