All supports require LOS some can get around it a little but not by much. Also people who complain about support LOS are usually that DPS that runs off to the other side of the map and dies alone then complains about “no heals”.
Zenyatta has the same problem.
Not by much and that’s less of an issue for people who can aim.
Only an issue for people who don’t communicate and people who are easily flustered.
She could use a minor buff or two but beyond that it’s probably just people who normally play DPS are flexing and losing on her.