If someone asked you how to do something, would you act it out, using no words at all?
Of course not. Yet, in our increasingly post-literate world, it seems like organizations are afraid to use prose. It doesn't cost anything, and when you post a link, you have all the room in the world to clearly write out a narrative of how something works. You can even do it in 200 languages without too much trouble.
Here's the fundamental mistake that marketers make: Great design often needs little explanation. And so, natural, organic, effective design often comes without written instructions. But, and it's a huge but, the converse is not true. Shipping something without instructions doesn't mean it's a great design.
What are the chances that a guest is going to use this hotel shower properly the first time?
Why does Ikea believe that providing nothing but little pictures is the best way to teach someone to do something?
After wasting hours trying to figure out the proseless instructions for a fancy lamp I purchased from an Italian company, I wrote a narrative for the company, in the vain hope that perhaps they'd save other people the trouble.
Most people would never choose to read it. Except the people who are stuck and confused, which is precisely the group you write instructions for. When in doubt, write it down. By all means, you still need pictures, even video. But there's nothing to replace the specificity that comes from the alphabet. Use labels. Use words.