Validation tools will also tell you if you have an H1 in a <section>, but no H1 outside of the section, because the <section> actually creates it's own scope, thus your page has no H1.
Looks like that kind of validation was premature. They mention in this article that the “creates its own scope” part was never actually implemented for accessibility, this change brings the display rules back inline with reality.
ricardobeat|10 months ago
radicalriddler|10 months ago
The difference between W3C and what browsers actually implement, if you don't laugh, you'll cry.