At the heart of web design is an important question: who is the web for? Is it just for a certain class of people, or is it for everyone? It is all too easy, when building a website, to not take into account the wide variety of levels of ability of your users. For example, if your website relies heavily on color to convey information, what happens when a colorblind individual tries to use it? They end up having a worse experience, or not being able to navigate it at all.
“Accessibility” simply means that your website is for everyone, not just for yourself and people like you. It is a way of creating content, and content creation tools, that takes into account a wide range of disabilities: auditory, cognitive, neurological, physical, speech, and visual (Henry). Each of these presents a potential hurdle that can lock people out of your website, and out of the whole communal process of creating the web, in general.
There are many concrete reasons to prioritize accessibility in your web design. It makes websites generally more usable for everyone, it pushes your team to come up with creative and innovative solutions that can give you an advantage, and it simply expands the size of your potential audience (Henry, et al). Taking potential disabilities into account has the additional effect of making it easier for everyone to use, pushing you to make it easy to navigate and presenting itself in a clear and precise way.
For example, to accommodate visual disabilities, you may change the colors of your website to be higher contrast, so those with low vision can still navigate it easily. This also makes the website easier and more pleasant to read for all users, and thus more appealing. It is not a concession to make your website accessible, but a goal to aim for. It will make your content more appealing to everyone.