Currently, the most active discussion thread on the HTML working group’s public mailing list, public-html, is one regarding the issue of whether in HTML5 the
alt attribute should always be required on images. And Henri Sivonen is among the most active participants in that discussion, posting to that thread (among other messages), the following:
The question of whether or not
alt should always be required is an issue that affects the behavior of validators, so it shouldn’t be much of a surprise to see Henri taking interest in the discussion around it, because he maintains a validator (more precisely, a conformance-checking tool) called Validator.nu that he’s spent a lot of time developing and that he clearly wants to be a beneficial and serviceable as possible to the people who take time to use it.
Among the assertions that Henri makes in his postings to that thread is the following:
An HTML5 validator isn’t an accessibility evaluation tool–or at least I think it shouldn’t be.
He goes on to compare the purpose of a validator to that of a spell checker, and in a later message, adds this:
A validator cannot check that a page is semantically correct. It can’t properly check for accessibility, either.
We should dispel misconceptions about what validators do instead of catering to the misconceptions.
And to clarify what he intends Validator.nu to be useful (and not useful) for, he adds this:
The validator I develop is not a stamping tool. It is a tool that helps authors detect mistakes that they didn’t intend to make, so that they don’t need to spend time wondering about the effects about their unintentional doings. For example, the validator I develop helps author detect that the alt attribute was typoed as ‘atl’, which is useful, because atl wouldn’t work… I’m not interested in developing a formal stamp. I am interested in developing a development tool.
The assertion that earning a “this page is valid” stamp or badge should not be an end goal (or any kind of goal at all) for users of a validator or conformance checker is something that Henri has stated consistently since the earliest public versions of Validator.nu were available (and that others have been stating for quite a long time also) — as is the assertion that a validator should be a development tool, not a tool for advocacy. Henri states that most succinctly is a section of the Validator.nu FAQ:
Validation is a tool for you as a page author — not something your readers need to verify.
To make a somewhat ham-handed analogy of my own: Consider the case of when you create a document with a word processor like Microsoft Word or whatever and you run in through that application’s built-in spell-checking and grammar-checking tools to find and fix any spelling or grammar problems. You’re using those tools as an author to ensure that the document doesn’t contain any unintentional errors before you share it with others. And after you use them, you would never consider embedding a badge in the page to indicate that it’s free from spelling and grammar errors — because the fact that it is free from such is something of real value to you as an author, it’s of no value to have it highlighted to all your readers, and not something you want or need your readers to verify.
Anyway, that (bad) analogy aside, I think Henri and most other reasonable people would agree that there is great value in encouraging authors to produce valid content, and beyond that, to encourage authors to be familiar with best-practice accessibility and usability guidelines and to try to follow them to the best of their ability. The main difference of opinion here is around what role (if any) validators should be expected to have in encouraging authors to do those things.