Fair enough, although is Java specifically the only language that could do this?

It surprises me that people turn to Java instead of say Go or Elixir or (keeping on topic with the article) Swift?

There is a long tail of other languages. JaneStreet uses Ocaml. I wouldn't be surprised if there was some usage of Go out there. I'm familiar with at least one trading house that uses Elixir. The bulk of it is Java or C++ though.

Due to language features, ecosystem and tooling, neither Go nor Elixir are even close, in what Java has improved upon since 1996.

Swift is mostly Apple platforms.