One common use for HTML even for people who don’t write web pages is for marking up blog comments. If you’re commenting in a blog, and the blog says that it supports HTML, it will let you use HTML to emphasis text, add links, and sometimes even add images. Usually, this will mean the emphasis tags, the meaningless markup tags, and links.
If you’re writing a blog comment, and it lets you use link tags, it’s a lot nicer to make a link with the real URL, rather than making a compressed URL as is often done to save space. It helps people who are careful where they click see where the URL is really going.