Many (most?) chocolatey packages are essentially two lines of plaintext configuration: the URL of an MSI, and the command line arguments used to run it silently. Chocolatey does add some value on top - metadata, tracking what you've installed - but all that is entirely separate from the MSI database that Windows already uses to do the same sort of stuff. The biggest value of the main chocolatey package repo, in my opinion, is that it's effectively a curated list of direct download links for MSIs.

EDIT: I forgot that it can also verify checksums, there is obviously value to that.

I did not know this... I might actually have a proper look at Chocolatey now. Thanks!