@tdg8934 The thousands and thousands of commercial games on the Switch were published by people who paid their official membership dues and got a dev kit from Nintendo-- then Nintendo goes through a vetting process when one of those publishers wants to push bits out into the ecosystem. These games were developed using pre-built engines, like Unity or Unreal, or written from scratch in C++, on PCs.
But us Fuze users have not paid our dues, nor does anything we submit go through Nintendo for vetting and approval: the Fuze guys have their own server, we upload things to them, not to Nintendo. Hence, Nintendo is very reticent about this ecosystem "back door", and has policies in place to prevent that door from getting thrown open too far.
To my knowledge, other contemporary GCS's on other closed, proprietary platforms have similar restrictions: when I was tinkering with "Dreams" on PlayStation 4 during "early access", there was no way to import external content there either.