Frankly, she can't 100-0 somebody with ult alone without landing anything else, unless considerably ahead.
...or that ADC having no MR whatsoever.
Still the problem with her ult isn't the damage, believe it or not. It's the availability of it.
Thanks to the cancer MYMU you grab some CDR and you can walk with 7-sphere ult at all times.
Before MYMU it had to be set up durning an engage which took about 10 seconds and had a window of like 2 seconds to be used and should you miss it, you had to redo the whole thing from scratch.
That's why the most common ults were 5- and 6- sphere ones, which aren't able to 100-0 anyone, except for that one guy who was AFK for 10 minutes.
I'm sure you can see how it was fair back then.