Quoting the author from r/rust[0] > Its paid features are always enabled when completing Rust code, in acknowledgment of the fact that TabNine could not exist without the Rust ecosystem. Thanks for this, Jacob! [0] - https://www.reddit.com/r/rust/comments/9uhc1x/tabnine_an_aut...
That's odd, because it could indeed exist without the Rust ecosystem. The author just opted to write it in Rust.
Not everyone has infinite time for development. If Rust was the only language they could get to the performance they want, with all the features, in the time available then the statement is valid.
Note that they talk about the ecosystem, not just the language. If you want a high performance, compiled language, with a good ecosystem of packages that you can leverage then Rust is a great choice. Arguably Go is the only other language that would fit the bill, but for some people the simpler type system doesn't allow the abstractions they want.