If you use her original recommended items following her release: triforce + ravenous hydra + warrior enchantment you will do a very high amount of damage, and that will not make her squishy, because she has room for two tank items. People are under the illusion that her one knock-up makes her a cc machine, when in reality, she is jungle-bruiser with high potential for map presence, so they end up playing and building her like a super-tank.
Also, she was broken on release, like extremely broken to the point where you couldn't just laugh it off (out-healing a fiddlesticks who had full build). Right now she's in a happy place so long as you build her with the proper items in mind, but most people are too dumb and short-sighted to be able to think on their feet, so they build the same useless crap, accomplish nothing, and blame it on the champ being bad, resulting in them giving up and finding a different champion to play.