Even in my small area of astrobiology, the design of a single mission to find habitable planets orbiting other stars requires substantial input from the studies of astrophysics, space communications, space flight technology, optics, materials science, the interplanetary space environment, Earth's atmospheric system, microbiology, geology, computing, remote sensing, and signal processing. Within each of those areas, input from many sub-disciplines is required. For example, in the "astrophysics" portion of my work I communicate from astronomers from all across the field. Some of them know all about the variability of stars, some of them know about the multiplicity of stars and giant planetary companions. Some of them are experts in the details of previous observing campaigns that have collected the data that I now need. And this process of information gathering goes on and on. In science, we need people who can go deep, and people who can go broad. My colleagues and I can literally create new knowledge and capability simply by networking and pooling our talents. I am the kind of person whose purpose in the community is to build bridges between areas of knowledge and begin unfolding the bigger picture.
The appropriateness of cross-disciplinary sharing depends entirely on the situation to which your knowledge is being applied. The Fire Department does not need my knowledge of astronomy in order to douse a chimney fire, but they might like to know and prepare in advance if an asteroid is about to impact our town!