The standard argument here is that the maintainers of the core technology are likely to do a better job of hosting it because they have deeper understanding of how it all works.

There's also the trick Deno has been trying, where they can use their control of the core open source project to build features that uniquely benefit their cloud hosting: https://til.simonwillison.net/deno/deno-kv#user-content-the-...