create_form(locals()) is so elegant! Each API endpoint is almost entirely described by the method signature alone, about as DRY as can be. Very clever (the good kind!)

+1, exactly this.

As an aside, “stop the world” GC pauses can affect web server performance in interesting ways. Some web application servers have a perf profile where throughput drops off a cliff as the server approaches max memory load. This is fine, so long as you know what’s happening, and can tune your auto scaling to spin up new servers before you start to hit that threshold. This likely wouldn’t be a reason to not use a particular lang / server, except at the most massive scales.