my favorite example of this was the go authors refusing to add monotonic time into the standard library because they confidently misunderstood its necessity
(presumably because clocks at google don't ever step)
then after some huge outages (due to leap seconds) they finally added it
now the libraries are a complete a mess because the original clock/time abstractions weren't built with the concept of multiple clocks
and every go program written is littered with terrible bugs due to use of the wrong clock
https://github.com/golang/go/issues/12914 (https://github.com/golang/go/issues/12914#issuecomment-15075... might qualify for the worst comment ever)