Then you just weren't paying attention. There's a list of approved languages for new development and Rust isn't on it. There's a list of languages that are forbidden, for which you need high-level approval to use for new work, and Rust is on that one, next to C++.

Rust support is categorized as Tier 2 at Dropbox. Do you work at Dropbox? You can go look for the language approval list, which documents this.

Tier 2 means it requires approval. That is massively different from "forbidden". There is, for example, a Tier 3 list - Java is on there, some other languages, they're discouraged a lot more strongly than Rust though you'll still find them in some parts of the codebase (primarily acquired code from what I recall). Approval is only required for business/ product dev - non product teams can very easily write rust, at least one is currently doing so.

Tier 2 means it has internal library support, such as the communication library. That means there is, at all times, active rust development - and of course this is true, the most critical parts of Dropbox are written in Rust, and they rely on those libraries.

You can also very easily find out about the existing projects being written in Rust. Go ask the rust-lang channel. Last I saw, maybe 6 months ago, Rust was being used for another major component of the product - obviously I'm not commenting publicly on that further.

You've (probably unintentionally, judging by your tone) shined a light on the corrupt culture of that engineering org. It's written down that Tier 2 languages require special permission to begin new projects. It doesn't sound like we disagree on that. The corrupt cultural aspect is there exists an in-group clique of engineers who can and will start projects in any language they want, and an out-group against whom the written policy will be used to stop new efforts.

It is definitely not the case that any randomly selected backend engineer at that company can just pick up Rust and solve any problem with it, because the Tier 2 status is used as a cudgel to stop most such efforts.

I disagree entirely with the "forbidden" wording. That's it. Tier 2 is not "Forbidden" it is a statement on the level of support.

I agree with your point about political issues - the entire tier list, specifically even Rust being tier 2, was political. I saw stupid shit like that too many times at Dropbox.

But it is simply a fact that new projects are being built in Rust, regardless of the political aspects of why that is the case despite it being tier 2. "Forbidden" does not convey the state of things - everything else you've said is agreeable.