It sounds like Netlify is essentially reselling a third-party service here. Isn't operating infrastructure Netlify's job? Why outsource this? Can requests end up taking circuitous paths where Netlify and Deno's infra don't line up?
Netlify also uses aws and rackspace . They are in the business of selling PaaS on top of IaaS by adding value to developer workflows .
They could host their own infra at large enough scale when that makes sense, the same way AWS decided after many years to make their own chips (graviton), but that is not their core identity like AWS is not a chip manufacturer.
It uses Deno Deploy for the actual execution of the function, but the whole workflow around it, routing and middleware API, integration with frameworks and the CDN are all Netlify. It's similar to how Netlify Functions use AWS Lambda for execution. It does add latency, but it's tens of ms, because it uses Deno Deploy nodes that are very close to the Netlify edge nodes. Deno Deploy is awesome, but Netlify has a much more complete platform, so the combination is best of both worlds.