The argument one's making is that at some point, the complexity of business rules extends the complexity of the DSL you wrote, at which point people tend to evolve DSLs until they become a crappy general-purpose programming language.

For a good example of that, see the evolution of template engines in web development. They quickly accrued conditionals, function definition, recursion, and at some point they just turned into a crappier version of PHP. The latter is doubly ironic when you see people using template engines in PHP, as if not noticing that PHP is already a better templating language.