DSLs communicate wonderfully with the business users paying for the program. It also allows a programmer to match the jargon / industry speak used by the users.
I know that Cadence's ASIC design tools are based on a custom Lisp dialect. I've seen a presentation at a Lisp conference from an architect who was representing myriad building regulations as Lisp expressions e.g. minimum clearance between toilet and bathroom door. There was another presentation about Lisp software for simulating aircraft engine performance based on various input parameters.
I don't know how close these applications are to Racket's ideal but I imagine they're somewhere on that spectrum.
If you start talking to older architects and civil engineers who where active in the early to mid 90s, you'll be surprised how many of them know (or at least knew) Lisp.
Oh, I whish ruby had a more formal way to switch to DSLs - I love ruby, but can't stand meta-heavy/DSL-heavy subsystems. The rspec test system is a prime example (saved to some small degree by its excellent and detailed documentation): https://rspec.info/
An ingredient that may contribute to judgment of this video testimony, is that the same person that describes this toxic environment accuses someone providing a different personal impression of the community of engaging in "micro-agression" in the video comments.
He acknowledged that Racket has excellent documentation, a wide-ranging toolset, etc. All the good stuff you've heard elsewhere.
He criticizes the language-oriented model (in comparison to languages that people are familiar with but that allow embedded Deals, like Lua or Ruby) because creating a new DSL is antithetical to code that communicates with other programmers. This is fair, and a common criticism of Lisps: the complete freedom of the macro system means that individual programmers can create their own dialects quite easily, and other users of that code have a harder time working with it than in languages where there's not as much metaprogramming.
On the "toxic" front, one of the core team apparently asked a waitress a cringy question about higher education, referred to some other educators (at the creator's institution) as doofuses and the like, and was arrogant.
And at the end of it all, though he doesn't see a use for Racket's language-oriented model, he recommends learning and using it.