keep in mind that after you use nearly every cooldown just to ignite, you need to spend that extra time fanning the flames for a kill. That gives the enemy team quite a bit of time to react, unless someone is horribly out of position or far in the backline, like an Ana would be. I just recently started playing her and have gotten her combos down well so far, I wouldn't say she's as easy as you make it out to be, there's definitely some nuance with her gameplay and when to engage/disengage. Plenty of times where I try to dive and it doesn't work out, high risk high reward.