Let's be straight: collaborative working is hard work. It takes everyone involved to be fully committed and it requires on-going attention and it needs support in order to sustain it. It's even harder as more people get involved: people from different organisations, with different objectives than yours and different cultures, locations and different reasons for even existing.
All of this complexity is typical of a supply chain. So, given that complexity and given how difficult it is, you'd be forgiven for asking, why even bother? Can we not just do our thing like we always have? Why do we need to work closely with a supplier?