tokio and serde are certainly not the only ones. You can put almost all of my crates into that category too.

The problem with your framing is that you look at this as a "dependency addiction." But that doesn't fully explain everything. The `regex` crate is a good case study. If it were a C library, it would almost certainly have zero dependencies. But it isn't a C library. It exists in a context where I can encapsulate separately versioned libraries as dependencies with almost no impact on users of `regex`. Namely, it has two required dependencies: regex-syntax and regex-automata. It also has two optional dependencies: memchr and aho-corasick.

This isn't a case of the regex crate farming out its core functionality to other projects. Indeed, it started as a single crate. And I split its code out into separately versioned crates that others can now use. And this has been a major ecosystem win:

* memchr is used in all sorts of projects, and it promises to give you exactly the same implementation of substring search that the regex crate (and also ripgrep) use in your own projects. Indeed, that crate is used here! What would you do instead? If you were in C-land, you'd re-roll all of the specialized SIMD that's in memchr? For x86-64, aarch64 and wasm32 right? If you haven't done that sort of thing before, good luck. That'll be a long ramp-up time.

* aho-corasick is packaged as a stand-alone Python library that is quite a bit faster than pyahocorasick: https://pypi.org/project/ahocorasick-rs/ There's tons of other projects on crates.io relying on aho-corasick specifically, separately from how its used inside of `regex`.

* regex-syntax gives you a production grade regex parser. More than that, it gives you exactly the same parser used by the regex crate. People have used this for all sorts of things, including building their own regex engine without needing to re-create the parser (which is a significant simplification).

* regex-automata gives you access to all of the internal APIs of the regex engine. This is all the stuff that is too complex to put into a general purpose regex library targeting the 99% use case. As far as I know, literally no other general purpose regex engine has ever attempted this because most regex engines are written in C or C++ where you'd be laughed out of the room for suggesting it because dependency management is such a clusterfuck. Yet, this has been a big benefit to other folks. The Yara project uses it for example, and the Helix editor uses it to search discontiguous strings: https://github.com/helix-editor/helix/pull/9422 (Instead of rolling your own regex engine, which is what I believe vim does.)

This isn't dependency addiction. This is making use of separately versioned libraries to allow other projects to depend on battle tested components independent of their primary use case. Yet, if people repeat this kind of process---exposing internals like I did with the regex crate---then you wind up with a bigger dependency tree.

Good dependency management is a trade-off. One the one hand, it enables the above to happen, which I think is an objectively Good Thing. But it also enables folks to depend on huge piles of code so easily that it actively discourages someone from writing their own base64 implementation. But as should be obvious, it doesn't prevent them from doing so: https://github.com/BurntSushi/ripgrep/blob/ea99421ec896fcc9a...

Good dependency management is Pandora's box. It has been opened and it is never going to get closed again. Just looking on and calling it an addiction isn't going to take us anywhere. Instead, let's look at it as a trade-off.