Those are two somewhat recent examples I can think of, but there have been many more showing the same kind of attitude.
They are ignoring hard-earned knowledge on how to do things securely, safely and reliably, they ignore the intentions of abstractions, and they pretend that obvious bugs aren't bugs because there is some weird way to reinterpret the bug into being correct behaviour (that noone expects and that causes harm).
By domain knowledge how to do this securely in implementations tested oer time, do you mean something like https://access.redhat.com/articles/2161461?
It doesn't look like systemd's resolver fares worse in comparison... In addition it can be sandboxed (and is), an advantage over having a resolver part of libc.
Would you mind explaining how exactly sandboxing prevents cache poisoning?