But browser engines are entirely functional based on open standards!!!!!
This is the core proposition!
The benefit of open standards here, is to the consumers of these standards .. not the engines.
Open standards allow the consumers (websites / apps) to be able to benefit.
The presumption that started this thread is that open standards are always good for competition. I think browsers are a good counter example where open standards led to three browser vendors, we have less competition rather than more.