They can in some cases. But what the FA-18s can't do is FOB to one of the short strips in Afghanistan. The advantage STOVL offers is that it can get in very close to the fight to maintain exceptionally short reaction times via GCAS.
My main point to Widger was that operating purely off the carrier is not the panacea he suggests and is certainly not viable in todays ops. STOVL, just like a carrier aircraft, will always be a compromise. STOVL offers far greater flexibility in basing at sea and certainly on land albeit at the expense of performance and payload.
It's a tough call which would be better and I can see arguments on both sides. As I said, if it was up to me I'd probably take F-35C as it still has a relatively short T/O run.
One has to wonder however if the RAN approach of smaller LPD will turn out to be more realistic than gambling a services future on 2 x 65 000 ton behemoths. No they won't have the same sortie generation rate as CVF. But they look to me to be more affordable and realistic than CVF right now.
I hope I'm wrong.