The best thing that ever happened to Cloud Formation was the new YAML syntax.
Writing YAML is easy with a good editor like VSCode. Install the YAML code outline extension for sugar; works great for OpenAPI specs. YAML flow style offers some good options for keeping the file compact.
I'm all for good editor support, but you shouldn't need it to write a simple document. Complicated editors should be supporting tools at best, because you won't always be in a position to use one. The things we write should be simple enough to be written and understood by hand with minimal mistakes (then we can make it even easier in some cases using nice editors and tooling).
I don't think I've ever used anything under than vanilla vim for editing YAML files... with next to zero issues.
The problem for me is that the multiple ways to do the same thing result in something that's pretty opaque to clear specifications that aren't just very simple examples / structures.
Writing YAML is easy with a good editor like VSCode. Install the YAML code outline extension for sugar; works great for OpenAPI specs. YAML flow style offers some good options for keeping the file compact.