As wOxxOm states, the Web Hypertext Application Technology Working Group standard specifies that, if omitted, certain tags are implied. The <body> tag spec states the effect of omission.
Some examples are given of expected browser behaviour in case of tag omission in the 13.1.2.4 Optional tags section.
What I thought was a lack of rigour by chrome was actually spec driven behaviour ensuring that poorly formed/ non- HTML is parsed.
Thank you for the links wOxxOm .
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