from my experience, heating has plenty of reliability deficit, probably getting way worse in recent years. fancy boilers with computers in them break way more often than they have any right to.
There is something to be said about the dead simple ways of things for sure, and all depending on object/item but a "sweet spot" where something is pretty darn efficient yet not overly complex.
Our endless forwards towards "the most efficient" everything always carries consequences. People / society included.