BLOCKING=RENDER: WHY WOULD YOU DO THAT?!

Summary from the TLDR Web Dev newsletter

The "blocking=render" attribute allows developers to explicitly mark resources as render-blocking, meaning the browser will not display the page until the resource is loaded. However, this is generally not recommended, as it can negatively impact performance. The most common use case for "blocking=render" is in client-side A/B testing, where it can prevent a jarring experience for users by making sure that the page is not rendered until all variations are ready.