If you don’t consider accessibility, you will exclude some of your audience, meaning your message will not be delivered as effectively as it should.
Accessibility starts at the very beginning of the communication process, every time: it should never be an afterthought. Think about the different needs of your audience, and understand that people process information in different ways.
This doesn’t just apply to people with permanent disabilities. Everyone will have different needs at different times and in different circumstances. By removing barriers for people with disabilities or learning difficulties, you will make the experience better for everyone.