Because when you beat the PL champions home and away, it wasn't in the groups ...
I don't think you're good enough to 'walk all over' the likes of Napoli and PSG. Of course you can beat them, but it won't be easy. I don't think you'd have beaten City home/away if it was in the groups, they only lost the second leg because they got stretched chasing the first leg lead, they also had a goal wrongly chalked off while 1-0 up. Also, Roma then gave you a tough tie which you won on aggregate, and they're a worse team than either PSG or Napoli.
You're a very good side and dangerous, but I don't think you'll get through that group 'comfortably', it'll be tough.