finding a supplier and getting everything approved to buy from them takes months/years. Which means once you find one, they have about as much power over you as you do over them since they know you can't just snap you fingers and buy from somewhere else.

I've seen a single vendor bring a billion dollar company to its knees. And if the billion dollar company decides to get all high and mighty and bring the full weight of their legal team down on the vendor's head, all they will do is bankrupt their vendor...which only makes things worse.

I've seen draconian, short sided purchasing policies lead to most quotes for business coming back with no bid. Many times, parts end up single sourced simply because they could only find one sucker who would accept the terms.

Might be good in the short term, but it will probably be more expensive in the long term.