From the accepted answer to What are some better alternatives to help files? on Stack Overflow:

If you have to write a help [file] you have already failed in your program design. Have you ever seen a help menu on your iphone or on facebook? Millions of average Joe people use them every day without problem.

I’ve heard a lot of variations of this sentiment, like, good software doesn’t need directions and manuals are bandaids for bad software. I don’t know where this bone-headed trope came from, but the idea that good user interfaces don’t require documentation is just not rational.

Even if we take at face value the idea that prominent devices and software, like the iPhone and Facebook, represent the pinnacle in interaction design—although many find that is not the case—it’s incredibly rare for such products to be shipped without some method of instructing users. For example, iPhone 4 ships with the cleverly-titled Finger Tips [PDF] getting started guide to show new iPhone owners how to turn the device on and off and how to make phone calls. Likewise, Facebook offers a vast help site to answer questions ranging from How do I log in to my Facebook account? to How do I create Facebook Ads?. If such great accomplishments in user interaction are still shipping help and manuals, are they wasting time, effort, and money on a signature of bad design?

In reality, all but the most simple tools require instruction in their use. And I’m not even entirely sure about that; even the earliest tools, like pointy sticks and clubs, push the limits of instruction-less use. Carefully-designed tools often stump otherwise technology-competent people.

For example, the first time I used an Apple iPad, I could not immediately turn the device on. My initial guess about how to turn on the device based on my experience with another Apple iDevice—a classic iPod—failed: in contrast to the iPod, the button on the face of iPad does not wake the device. Likewise, my second attempt to wake the device failed too: the apparent black button on the right edge is actually a volume toggle. The actual power button is on the top edge of the device and, like all of the buttons on the iPad, is unmarked. Without some well-timed pointing on the part of the device’s owner, I would have given up without getting even that far. Other features of the iPad, like pinch-to-zoom gestures, are even harder to deliberately discover (if you even knew they existed).

I’m not saying a help file, printed manual, or video tutorial is the only way to impart usage information. For instance, some video games do an excellent job doing interactive training of which the player is nearly unaware (Half-Life 2: Episode One’s in-game commentary mode has a brilliant explanation of how this training can be put together). And certainly, if all other things are equal, better interfaces will require less instruction. But I remain totally unconvinced that good user interfaces can be made without some kind of instruction. Even the 2.5-year-old iPad user relies on the implicit instruction of seeing and using the similar iPhone.

Instead, I offer this alternative to idea that good software doesn’t need documentation: if you haven’t considered how you’re going to teach the use of your software, you have already failed to create a usable tool.