It's amazing that people cannot comprehend just how difficult writing a non-toy free OS is when all software is proprietary.

They think that Linus and a few buddies could have just written an OS from scratch with no free compiler and no free buildsystem and it would have turned out functionally superior to existing Unix's.

They literally believe GNU did nothing important, in utter ignorance of the difficult of writing a free software compiler that had an acceptable optimizer from the get go and evolved into a better optimizer than all previous proprietary software and writing replacement to all of the Unix software that is also faster and more reliable.