Agree. Italy has in the past deployed the military to keep cruise ships and their tourists out of Venice. Because even if you deny them from docking there, they'll just dock somewhere close by and charter a bus. Lots of 1-day-tourists means lots of dirt and trash and dangerously crowded roads in and out of the city. And since most cruise ships are all-inclusive, those tourists pretty much won't buy anything. They stay exactly 1 night at each location, so they cannot even afford to buy a meaningful souvenir because then they won't have budget left for souvenirs at the next 10 stops.

So yes, "cruise ship tourists ruin the economy" is probably the best argument for getting the locals on your side.