Someone pointed out that Google is not really a search engine any more. It is an AI machine that tries to interpret your meaning rather than search for what you ask for. As such, there are sites that are very likely to be part of their index, but which appear to be impossible to pull up in a search. Even using quotes, the plus sign, the minus sign, and site won't be enough to overcome its guess about what you really meant to search for.

All of that matches my experience, but I don't believe that makes #Google not a search engine, even if it makes them not very good at search.