Which practice should HTML5 avoid?

HTML5 aims to promote standards that ensure compatibility and functionality across a variety of devices and platforms. Taking advantage of the most up-to-date plugins does not align with this goal because plugins can create dependency on specific software that may not be universally accessible or supported across all devices. This can result in a fragmented experience for users, as not everyone will have the same plugins installed or enabled.

In contrast, being device-independent is a fundamental principle of HTML5. It allows web applications to function across a wide range of devices, including desktops, tablets, and smartphones, without relying on specific hardware or software setups. Similarly, using markup instead of scripting where appropriate is encouraged because it enhances accessibility and ensures that content is structured semantically, improving the overall user experience.

Thus, the emphasis in HTML5 is on building robust, flexible applications that do not depend on additional plugins, which can hinder accessibility and uniformity across different browsing environments.