As you mentioned when you work, you will get involved with different people with different background and personality. Having people with different background and experience helps the whole team and the project in general if you utilize the resources well. Diversity helps to build a strong team and progress or projects in my opinion. An example is I work with a different group of engineer and sales engineer, and the difference of personality helps me to build an idea and understand their working style which is different from a person to another. Also, It helps to know who is the key person to do something based on his past experience. Like I can approach more that one person for the same task, but having a different background on your team you will choose one that you know he/she will do the job faster and more efficient.