Great suggestion - I've read some of their UI guidelines, but I'll have to check out more. I don't know what the specific language you're referring to is, but

Great suggestion - I've read some of their UI guidelines, but I'll have to check out more. I don't know what the specific language you're referring to is, but I do imagine an issue with expressing "the main operation of the website or application" too prominently in something like a marketplace. Imagine if eBay or Amazon tried using a huge splash that took up the entire area above the fold to explain what they were about. I guess you could argue that in a marketplace type of site, the "main operation of the website" is expressed through displaying all of the various items for sale; but that's not the type of design that would come from the thought process this article warns against. PS not saying that's what you're implying, just observing.