It's a weird argument to me that somehow obtaining a Java runtime environment is easier than getting a binary for a Scheme interpreter. I think most people who aren't already Java users would find the latter easier, not the former.
That note in the docs is from a time when Emmy only ran on the JVM. Now Emmy runs in JS in a browser (see my top level comment for demo links) which I would argue is even easier.
Also the MIT scheme install was historically quite hairy and not supported on M1 Macs, for example.
