Comment by jasode

>, then you wouldn't put an ad on your site that wasn't valid XHTML,

You're overlooking how incentives and motivations work. The gp (and their employer) wants to integrate the advertisement snippet -- even with broken XHTML -- because they receive money for it.

The semantic data ("advertiser's message") is more important than the format ("purity of perfect XHTML").

Same incentives would happen with a jobs listing website like Monster.com. Consider that it currently has lots of red errors with incorrect HTML: https://validator.w3.org/nu/?doc=https%3A%2F%2Fwww.monster.c...

If there was a hypothetical browser that refused to load that Monster.com webpage full of errors because it's for the users' own good and the "good of the ecosystem"... the websurfers would perceive that web browser as user-hostile and would choose another browser that would be forgiving of those errors and just load the page. Job hunters care more about the raw data of the actual job listings so they can get a paycheck rather than invalid <style> tags nested inside <div> tags.

Those situations above are a different category (semantic_content-overrides-fileformatsyntax) than a developer trying to import a Python library with invalid syntax (fileformatsyntax-Is-The-Semantic_Content).

EDIT reply to: >Make the advertisement block an iframe [...] If the advertiser delivers invalid XHTML code, only the advertisement won't render.

You're proposing a "technical solution" to avoid errors instead of a "business solution" to achieve a desired monetary objective. To re-iterate, they want to render the invalid XHTML code so your idea to just not render it is the opposite of the goal.

In other words, if rendering imperfect-HTML helps the business goal more than blanking out invalid XHTML in an iframe, that means HTML "wins" in the marketplace of ideas.