There's many overcrowded spots on one hand, on the other hand, there's plenty of amazing places that get very little tourism, and if they do, they get it like 1/2 months per year at best. Florence vs the rest of Tuscany is a great example of this. Florence gets the lion share of the tourism in the region, despite all the provinces having major attraction places during all seasons for different reasons.
It's also time more governments and municipalities do something to increase prices in very hot spots. Squeeze those that want to spend properly and try to keep out lower budget travellers to less crowded places?
Low cost airplanes are part of the problem but privates renting their own apartments are the worst. They effectively double the places to sleep in major cities while also having locals abandon them completely.