What I gained most of the HTML is happiness as I now know how to identify tags and syntax in HTML or CSS of a website. Since I mostly blog on WordPress and Blogger, now I do not afraid in making changes in their CSS or HTML body. I gained a lot in designing my blogs as per my need or demand.
Knowledge of HTML is an added advantage if you are somebody that mostly writes about technical terms. On the other hand, if you are a writer about general niches, well then it can help you when you launch your own websites.
Another advantage of learning HTML is that you can use while making newsletters on Zoho or Salesforce or Mail Chimp. HTML is useful when you want to embed videos in your content. Adding videos in your content makes it look more credible and nice.
If you have time do learn about it, otherwise as a technical writer it is better you get yourself equipped with Python or R. HTML is now quite old and not in demand due to WordPress, only a handful of web designers use it. In fact, themes and plug-ins of WordPress back seated HTML – one of the oldest and widely accepted languages for browsers.
Once HTML used to be a forte of web designers; however, with time and technical advances, it’s no more regarded a great skill and people are paid even less than SEO guys.