Soggy conditions promote the growth of the kind of bacteria that thrives without air and that would in fact not grow much or at all in conditions with plenty of air. These anaerobic bacteria love to eat vegetative matter including Venus Flytraps. When the soil is kept too wet too often, these bacteria can easily begin to rot the "bulb" of the Venus Flytrap.
Venus Flytraps are not aquatic plants, nor do they prefer conditions as wet as many Sarracenia and Darlingtonia frequently experience. Venus Flytraps live in sandy savannahs, nutrient poor grasslands and barrens that have a relatively high water table, but are not swamps, lakesides or bogs, although Venus Flytraps can survive in some of those conditions under certain circumstances.
In cultivation, it is much better to aim for "moist, not wet" with Venus Flytraps. Of course you need to get them wet to water them thoroughly, but then the medium should be allowed to dry to just moist before watering again, or if using the tray of water method, allow the water to completely dry from the tray before filling it again, for example.
During dormancy with cooler temperatures and less light, never allow the plants to stay too wet for too long. I personally water thoroughly in the morning (only every 8-15 days or more) so that the medium can begin to dry out before nightfall and lower temperatures.
Moist, not wet; never soggy for long, nor completely dry.