The US government writing guide summarizes what people want from writing on the web:
When writing for the web, using plain language allows users to find what they need, understand what they have found, and then use it to meet their needs.
It should also be actionable, findable, and shareable.
Research shows that people don't read web pages, they scan. On average, people only read 20–28% of web page content. Reading from screens is much slower than reading from paper. People will give up and leave your site unless information is easy to access and understand.