Stop excusing them, they were the first to acknolowdge being wrong in first place,
"They are likely the two most difficult parts of any design for parametric polymorphism. In retrospect, we were biased too much by experience with C++ without concepts and Java generics. We would have been well-served to spend more time with CLU and C++ concepts earlier."
-- https://go.googlesource.com/proposal/+/master/design/go2draf...
What is there to excuse? Your quote confirms that they simply don't know what they're doing as was already established. Not that anyone should expect them to. They're just regular average humans, same as every other random Joe you encounter while walking down the street, who all equally have their own failings and shortcomings. Why HN is constantly trying to put these particular people on a pedestal, I'll never know. Jealously that regular bumbling idiots just like them accidentally stumbled into creating something popular (for some definition of popular), perhaps?