Some businesses can easily explain themselves:
On the other hand, my website's service is a long, complex process that I can't sum up into a slogan. It takes several paragraphs of explanation for readers to get the gist of "what we do," "how it works," "why choose us," etc. Nobody likes a wall of text on the homepage. How do I get conversions when people have super-short attention spans and won't sit down to read a long-ass article? How do I compete with other sites that have clear value propositions?
Premium rickrolling also has complex motivations and processes behind them. You just aren't interested in reading several paragraphs of text about it. Or at least not until after you know their slogan and they piqued your interest.
How to compete with sites that have a clear value proposition? Have one yourself. This isn't a UX problem in the sense that this forum means, it's a problem of copywriting.