I read some scary comments here. (By Blog page, he means the Posts page in the reading settings.)
The Blog Page gives out several indicators to social sites and Search Engines that it's a Blog. [...] In fact, WordPress requires a Blog page to be available. Failing to do so may cause bugs in some plugins and themes, and even within WordPress itself. [...] The Blog page is a reserved item within WordPress. Many WordPress functions and queries are written around this item.
Is the Posts page really required? Can problems with plugins or Google occur if I leave it blank?
(Reason for asking: I want to use a parent category "blog" instead of a Posts page.)