I agree. With a few exceptions, I've learned with good homework, I can cobble together a more effective and much cheaper sightseeing trip.
I also hate waiting pierside for all to assemble, riding motor coaches, eating std meals, getting hurried, and ending up at kickback souvenir shops on my dime.
That said, we've cut it close several times and once in Naples,Italy the gangway officer requested an explanation for the captain why we were late and holding up the departure.
We were on an electrified train from Pompei to Naples that got hit by lightning. We had le with plenty of time but with massive delay arrived at Naples station 5 minutes before sail time and 25 minutes after onboard time. Cabbie literally driving like James Bond on the other side of the road.something to talk about and more exciting than pompei. We were prepared to catch a train to next stop.