Accessibility entails making a work, whether it be a website, a program, or a picture of your dog, perceivable by as many people* as possible;
This entails complying as closely as possible to specs, utilizing tools in the most intended way possible, and making your delivery method as simple as possible;
It's not just about the visually impaired, or those with slow networks;
It's making your stuff able to be accessed under as wide a variety of circumstances as possible;
It fucking sucks to implement sometimes, but the observer shouldn't be expected to pick up the slack of the creator;
In short, observers should hold more power over how they observe a work than the creator does, because the creator cannot account for every possible circumstance under which their work will be observed;
*All sapient lifeforms, including dolls, AESIs, robots, intelligent animals, etc;
**Note that intentionally omitting information for the purpose of narrative is not held within this;