Writing for the web is very different from writing for print media. At first, the emphasis was the "stealth practice" of using lots of keywords, or metatags, to get the attention of search engines. They've gotten smarter, and that doesn't work anymore. The unique factor of content writing for a web site is the organizations analysis of how the information is to be presented, and therefore how to break it down into elements that can be logically navigated within the site. A web site is not organized in a linear format like a print publication. You can jump from page to page, and the sequence of how you do that is determined by the organization of the "home page," or "landing page."
The "jumps", or how you get from page to page are called links, and that is set in coded language called HTTP, or hypertext protocol. This coding determines the format, color, and connection within and between pages. You don't have to know how to write code to write content for the web, but it helps. The problem with programmers writing content is that they can become preoccupied with the formatting and forget that they also are trying to convey a message.
Unless it is a catalog, a web site is more than just a compilation of technical data. It is a sales promotion device that is targeted to very discrete audiences who are looking for more than just information. They want a "connection," i.e. an emotional trigger to elicit a response. That trigger may be a photograph or a technical specification that meets their needs or wants. In other words, it's a lot more than just about coding.