One of the least active WebmasterWorld fora is this one : Accessibility and Usability yet together (accessibility (a11y) standards and usability processes) they are the very foundation of what makes a site technically and functionally usable by people, not just those with typically named disabilities, i.e. sight impaired/blind, deaf, variously limited mobilities and cognitive difficulties. They also apply to folks with poorer literacy/fluency, lower bandwidth connections or older/mobile devices, etc.
Put simply, by their very nature a11y and usability require inclusion; the more the better. In effect, they underwrite both the breadth and depth of site visitors' user experience. Inclusion design aka universal design aka design for all is a thing. Look it up. While many webdevs at least think about site usability few even consider a11y, most of whom shrug and say too much of a pita.
Approximately 20% of any large population is, to some degree, functionally disabled. Yes, many can struggle through most sites but they do NOT enjoy the experience. Now add in those with technical constraints or environmental difficulties such as sun glare on screen et al... Is being oblivious to a fifth or so of one's market audience a good long term business model?
Since it's inception WordPress's Gutenberg editor has drawn a cacophony of a11y complaints/concerns from WP developers all of which were ignored until after actual release. WP is still playing silly idjit a11y compliance catchup with Gutenberg. Far more effort and cost than if they'd not been so wilfully ignorant/oblivious so blatantly so long.
Further, increasingly jurisdictions around the world are enacting or updating regulations regarding the web and the disabled. With ADA based law suits such as National Federation of the Blind's class action against Target, Aleeha Dudley (joined by US DoJ) vs Miami University in Ohio, Jason Camacho of NY vs. 50 colleges, just to name a few the legal fact and costs reality of ignoring a11y is beginning to strike home.
I admit that I was somewhat behind the curve regarding a11y until perhaps 2006 or so when there was an up surge in WebmasterWorld threads on the subject; or perhaps I finally woke up enough to notice. Subsequently I engaged with several very ardent experienced advocates over at Cre8 (RIP). Suffice to say that on listening and discussing and researching I realised the moral, the legal, and the value of building in a11y much as I had SEO et al. Initially, it was a manual template effort to meet WCAG 1.0. Eventually, during 2010-2012 I included a11y into the mobile first, context first, progressive enhancement renovation of my CMS; currently to WCAG 2.1 AA standard levels and am slowly adding AAA levels as I deem appropriate.
Four conclusions since 2012:
* due to analytics constraints the range is wide, however I know at least 9% of my visitors appreciate/utilise my a11y efforts and it conceivably may well be 17%. Either is a significant number in both relative and absolute terms.
* as I've mentioned elsewhere my direct ad space offerings are full page(s) native ads; that these are also a11y compliant is of increasing interest to advertisers and agencies and therefore also an additional justification of rates. Back in 2012 in my ad space presentations it was a mere mention in passing that was largely ignored, more recently it has become an additional 5-10 minutes both anticipated and appreciated then discussed.
* there are universities offering degrees associated with my niches. Their interest in my ad space has gone from none to mild to warm to hot over the past decade. Where commercial enterprises are primarily interested in converting traffic with a11y a nice addition academia while certainly wanting the referral traffic is laser focussed on the a11y sales point.
* one of the most prominent SM WoM drivers is the usability and a11y aspects of my sites. Not only enthusiastic recommendations but significant traffic generation.
Stop ignoring the Accessibility lense of your Accessibility and Usability glasses. Going about with one eye always closed is inefficient and counter productive. Really.