In a humid environment such as Singapore, regions in South-East Asia or any areas with high rainfall, fungal growth on lenses AND human body are pretty normal occurrence.
Dryboxes help lower the humidity inside the box itself and helps prevent fungal growth on lenses.
Its a slight cause for concern, but not to the point of paranoia.
Me? I place my cameras in my bag all the time. And I dun even have a dry cabinet to boot, just a dry box with silica gel. And no, none of my equipment had any fungal attack/growth. I guess it also depends on how well u maintain ur surrounding environment as well.