Arguably its bad food. Anyways its mass produced food that has no attachment to the place where it is consumed (outside the USA). Food, like the appreciation of a city, has a cultural aspect that McDonald's lacks.
McDonal's for someone visiting Europe makes no sense at all. You've dropped a few thousand in airfare and hotels, now you're being cheap on the food?? (Here I make an exception for Europeans eating McDonalds. They live there, they know their culture and their food. Go ahead stuff your pie holes just for the purpose of filling your bellies).
"Disneyland is also great."
idem for Disneyland. It's a fake image of a medieval utopia that never existed even in fairy tales. It's purpose is to create value to the Disney brand by becoming, through sheer force of the ubiquity of the Disney company, a part of children's childhood replacing real experiences and the myths handed down through generations. You don't learn anything at Disneyland, you do not grow as a person at Disney because there is no substance to Disneyland.
At best you have "fun", whatever that means. More likely you're told you had fun, and you repeat that to yourself to avoid admitting you mostly just waited in line.
Venice as Disneyland is a place where hoards of bucketlisters checkoff yet another selfie at Piazza San Marco (or is Piazza Spagna? who remembers? who cares!?), not for the San Marco's sake, but to pretend they accomplished something merely by buying a cheap ticket and airbnb.
You made it to Venice! Big deal! How hard is that?
No. A person who wakes up 4:00am to make it to San Marco at dawn to see San Marco alone has accomplished something (albeit small). A person who goes to Venice and doesn't go to Piazza San Marco, but instead spends the whole time alleys long forgotten by the hoard has accomplished something.