If your message is easier to understand, you'll reach more people.  Keep jargon, technical terms and long-form content for the audiences that need it. Plain English isn't dumbing down, it's opening up.

It's hard to keep audiences engaged. Clear communication gives your users exactly what they want. Help them find information quickly and they will respect you. They might come back for more. Business goals start with user needs.

Remove the friction. If your messages, marketing collateral and instructional information are clear, it's easier for customers to act. Clarity of message means less confusion. That's fewer calls for help, emails or complaints.