Why would be a TP more difficult than a Jet? I've done some old fashion TP aircraft simulator and there was nothing difficult about it concerning the procedures, just the handflying was more sensetive to inputs. But then again it was sim so I don't know about the real in-flight handling. But it looks quite like any Boeing or Airbus cockpit of today with all required automated and fligth guidance systems.
It's all question of training and getting used to it, it's normal for pilots that fly a jet like an Airbus for thousands of hours and will give it a try again on a TP will struggle in the beginning. I never met any person who would love to go back from jet to TP... only vice versa. So if the TP is that great to fly for, why does it's pilots always look for a jet opportunity?
There is no such thing the one is easier then the other. I guess it's an way of expression by frustrated TP pilots towards jet pilots who realise that they made the biggest mistake ever of taking a job on TP with the goal to advance in their carreer onto jet...
Times changed, but it's not only now, I remember even like 10 years ago a lot of people who flew TP struggled a lot to get a job on a jet or even never got it till today...
It's funny to see that ATR for example are copying the airbus cockpit layout with their ATR72-600! Don't forget also that TP's are flying at lower approach speeds and so you have more time to anticipate, prepare and correct while in a jet everyhting goes fast!