What that quote means is that you can take a Haskell program and compile it into lambda calculus and this is what GHC is more or less doing. This has important

What that quote means is that you can take a Haskell program and compile it into lambda calculus and this is what GHC is more or less doing. This has important implications. From a theoretical perspective, it's easier to prove that the language remains sound when you add new features. But also from a more practical point of view, it's easier to work on compiler backends for a more minimal language, to target new CPUs or for applying optimizations. These issues are very well known to language designers. E.g. one of the big changes in Scala 3 / Dotty is that it's supposedly based on "DOT Calculus". Having the ability to "desugar" the language into a simpler language that is provably type safe is pretty awesome. What makes Haskell interesting is that the developers using Haskell also become acquainted with such issues. Haskell is a language and ecosystem that raises the knowledge ceiling for its users. And there aren't many languages around that do that ;-)