To be fair, every time a new character is released, whatever they can do is moaned about endlessly since people havent figured out how to counter them. Anything that can burst down her shield is effective, and she's useless if attacked from more than one direction.
I'm a Lucio/rein main so I've learned to a) swing endlessly, rein wins that duel, b) make her head spin, either I get behind her or she turns her shield from my dps/tanks, or c) swap, the most elusive skill in Overwatch. Moira can lob an orb at her and keep distance while she zaps Baguette's shield, D.Va and Winston can burst down and zap through her barrier respectively (though Winston shouldn't 1v1 her), and most of the dps either have range or high burst damage.
Borgata's designed to hard counter a lot of the narrow focus of team comps we've had, it's going to take a bit for a community entrenched in dive and disapproving of almost any change in the game to come around to playing in a way where Borgia fits in as well as anyone else. Give it a month or two more.
All that said, I only just got back into playing regularly. The community at gold rank hurts my soul.