We'll agree with both of these statements, with a small asterisk.
1. Parenting is the hardest and most important responsibility for which there is no consistent guidance. Every parent should strive to do the best they can, and every parent wonders what could have been done better. The shape of a family (single parent, traditional nuclear, poly,...) will shape how great parenting is done; it must never alter the reality that great parenting is done, whether alone, with a partner, with other relatives, ...
2. Parents' sex life should be private. Kids need to know and understand that parents need "private time", and that everyone's private time has to be respected. That said, kids will be exposed to sex information from non-parental sources--friends, the internet, whatever. We will fully agree that parents should not be exposing kids directly to sex, our asterisk being that part of parenting is managing kids' exposure to--and responses to--sex information.
We'll close by remarking that we grew up when TV shows such as "Father Knows Best", the "Donna Reed Show", and "Leave it to Beaver" were in syndication if not first run. These "family" shows depicted imaginary (and aspirational) relationships. In these universes, "non-binary" was inconceivable, marriages were perfect, etc. The world is a more complex place, and contemporary kids know this from all sorts of messaging. None of that new messaging makes parenting easier.