Ask HN: How does FPT compare to tried tested techniques?

FPT - First Principle Thinking

When you are thinking through FPT mode, does one have to deny the existence of other presumed techniques. From the perspective of Physics I understand that the basic principles of atom and molecules will remain the same. However from the perspective of Computer Science how does this work?

Let's say I want to build an operating system, do I need to go so deep to throw out all the current implementations of memory management, scheduler management and create a new one or do I accept the current implementation as final and then build from there?