Minor correction regarding Zeta: It's still technically an emulator of a DOS environment - just an incredibly bare-bones one, with enough implemented to run ZZT/Super ZZT and little more. However, being made to run a specific executable lets it do some other tricks - such as reduce input lag or introduce an "idlehack" to prevent 100% CPU usage. Zeta was designed over a year before the Reconstruction of ZZT was even a seriously entertained idea, and I'd have certainly gone about it differently had I had hindsight.
Also, Zeta is a JavaScript/WebAssembly project in this regard (the C part of the codebase is compiled to WASM, but can also produce an SDL-based desktop variant) and developed as such; not just JS!
You're absolutely correct, of course. I was more saying that Zeta allows you to get ZZT without having to own a DOS machine or be good at configuring DOSBox.
Also, Zeta is a JavaScript/WebAssembly project in this regard (the C part of the codebase is compiled to WASM, but can also produce an SDL-based desktop variant) and developed as such; not just JS!