I heard a few other good reasons for following standards including accessibility and ease of maintenance. I left those out because they really don't matter so much for hackers. My intentions are to inform how following standards can save time building applications.
A lot of the "softer" justifications for building standards compliance websites, like accessibility, are just positive side-effects of following standards for more pragmatic reasons.
How is the validator gem used in rails? I'm thinking of starting a rails project and I'd like to validate every single produced page, every time it's produced.
I'd assumed the best way to do it would be cache the output and run the validator 'offline' but I couldn't find any rails or rack projects that do this.
I'm not sure, but I can say that it will slow your tests down quite a bit. If you're going to test every page you might just consider making your markup XHTML strict and test to make sure the XML is well formed.
I liked the bit about unspecified failure modes in HTML 4. Very important point, though I feel somewhat sad that such persuasion is necessary.
My way of looking at it is: you're trying to produce a certain kind of output that is externally specified and there are available 3rd party tools that can validate it. Why wouldn't you automate testing?
A lot of the "softer" justifications for building standards compliance websites, like accessibility, are just positive side-effects of following standards for more pragmatic reasons.