I don't really agree with that. Although Clojure has many great things, for example its out-of-box immutable data structures, I wouldn't say that it's "more modern" than Racket.

If anything, lately Clojure has been drawing on Racket for inspiration in many areas (for example Typed Racket).

In fact, if you wanted to find a criticism of Racket, it might be that occasionally it is "too" modern -- in the sense that some parts are implementations of research papers. You might encounter the occasional module whose documentation isn't much more than "Implements foobars in the sense of Researcher [Year] <link to paywall paper>". To be clear, that is not 98% of Racket. I mention it just to counter the idea that Racket is "less modern". It's constantly evolving with new things.

Finally, for someone getting started with a lisp, Racket is (a) download, (b) install, (c) start coding and running -- within literally 5 minutes. (Of course experienced people aren't limited to DrRacket if they prefer Emacs or Vim or whatever.)

The whole notion of a "modern" programming language is a big joke considering that mainstream languages have been playing catch-up to Lisp for decades.