Interesting point

good regards

There could be a lot of reasons and the most effected one is the communication. Without communication a team member cannot

1) Express his/her problems

2) Understand the task he/she is going to work on

3) Enhance his/her confidence

4) Refine his/her communication skills

5) Be more productive and much more...

All these facts are based on real industrial experience that's why I'm not referencing any case study or methodology here.