Peaches spoil faster than fruits like apples or pears for several reasons.
First, they have a different surface structure, with no natural waxy coating or thick epidermis to protect them from bruises.
Second, unless a fruit is completely dried out, normal metabolism continues and the fruit burns up sugar reserves; the peach respires at a higher rate because it is burning its sugars faster.
The higher the temperature, the faster the process.
Leaving peaches out at room temperature not only speeds ripening and aging, it also increases the rate at which rot organisms develop.
Another factor that may make peaches rot faster than they did just five or six years ago is the reduction in the use of chemicals to retard spoilage.