Recently updated in the Google HTML/CSS Style Guide (optional tags section):
Omit optional tags (optional).
For file size optimization and scannability purposes, consider omitting optional tags. The HTML5 specification defines what tags can be omitted.
(This approach may require a grace period to be established as a wider guideline as it’s significantly different from what web developers are typically taught. For consistency and simplicity reasons it’s best served omitting all optional tags, not just a selection.)
<!-- Not recommended -->
<!DOCTYPE html>
<html>
<head>
<title>Spending money, spending bytes</title>
</head>
<body>
<p>Sic.</p>
</body>
</html>
<!-- Recommended -->
<!DOCTYPE html>
<title>Saving money, saving bytes</title>
<p>Qed.
Moving to React from Blaze? Fine. Dropping Iron Router for Flow Router? Makes sense. Goodbye DDP, hello Apollo? I understand …
BUT THIS??? I honestly don’t think I can re-wire my brain to handle this … I guess it’s time to start a farm or something.