AMI has been the largest "independent" firmware vendor for quite some years.
One competitor was Phoenix, just acquired by Lenovo.
Only Insyde is left, having grown again over the years.
Those were the big three; all their stuff has been proprietary, NDA-driven business behind closed doors, providing barely acceptable (or worse) firmware for almost all laptop, server and desktop systems.
So now it's time for smaller firmware vendors to grow and provide better quality services.