Making a new language in Racket is just writing some functions (and macros, which in Racket are a kind of function). This means pretty much all your tooling comes along for free (syntax highlighting, debugger, etc).
The reason that someone might write a DSL is because it better fits the problem. The OP's example Pollen for instance, provides an easy way to run a full programming language to produce HTML output, something that can be tedious without language support.
Maybe I didn't explained it well on the post. Racket comes with many languages, not necessarily DSLs, some are full blown languages. People also ship new languages as packages. Pollen is one of such languages. The post details how I can leverage the fact that I can write Racket functions and use other modules and call them from Pollen. The main objective is to make people more interested in more flexible systems for blogging. That people should mould their blog to their experience and not the other way around (which is much more common).
I agree, it’s a turn-off, for sure
Also, debugging the compiler is not as daunting if you want to. I never needed. The DrRacket IDE comes with all the tools and workflows to make that just like debugging any other program.
Maybe it’s just my past experiences clouding my judgement, but if I see something saying it has its own language, or dsl, or flavor of a language… it makes me want to run away!