One of the many website design features which was once impossible, but has grown inexorably, is ‘hiding’ copy and making the reader click to read it. There are two main ways in which this is done: the first is simulating ‘tabs’, and the second is the ‘click to reveal’ method, usually marked by a ‘+’ symbol.
Both of these design techniques annoy me when they’re used badly – and they often are. One thing humans are great at is scanning a document for items of interest. A tab heading is not an item of interest, and whatever it’s hiding can’t be scanned without effort.
I guess the thinking behind hiding content like this is that certain data might only be of interest to a limited group of people, and for the rest, you don’t want it to get in the way of reaching the call-to-action. (In reality, the ‘design feature’ was probably included because it came with the template the designer was using). But calls-to-action don’t have to be solely at the end, they can be repeated down a page. So there could be one above the supposedly limited interest content.
One place where hidden copy is a valid approach is where it aids scanning, rather than hinders it. An example is the FAQs page. A traditional way of formatting this would be to have a series of questions and answers on a page, but at the top, have all the questions listed (for easy scanning), with each one as a link, jumping the reader down to the full Q&A below. The ‘hidden copy’ alternative is to have all the questions listed, with a ‘reveal answer’ button next to each. This, I suppose, is slightly more efficient, as each question isn’t listed twice. But that’s hardly a problem which needed solving.
If you have hidden content on your website, you’re not forced to do so. Opening it up to the world isn’t a major exercise.