Dark blue can provide an eye-ball to eye-ball presence for a lot longer than an jet. The Cod Wars spring to mind.
Whilst a Nimrod arrested a fishing boat it took a ship to bring it to port.
As an offensive platform otoh a Nimrod could reach places the ships can't reach in the outer defence zone - which probably wouldn't be needed if the CVS wasn't there in the first place and so it goes on.
A ship, whilst being a semi-permanent presence is also in a 'fixed' for a few hours whereas the aircraft is only fixed in time and space for a few minutes.
A ship can move out of harms way at 30 kts and aircraft can move out of harms way at 400 kts. The ship is also rather more vulnerable to mines, sampans, junks and submarines than an aircraft - provided the aircraft doesn't try and mix it too close <g>.