The main point of IDE is not code completion but lots of static and dynamic analysis to keep you from writing bad, slow, insecure, what have you, code.
Most of that stuff is proprietary and cannot be plugged into terminal.
The only attempt I’ve seen was actually by Jetbrains with Resharper beta for vscode
Eh, haven't needed it. Especially now that there are AI coding agents, but even before that. If I really wanted to run some static analysis in IntelliJ, always had the option to do it separately from my real editor.
That's mostly delegated out to language servers now. There's no need for Zed and Emacs and Vim and so on to each individually have to re-implement renaming a Rust function.
I also highly doubt that any IDE, whatever that is, is better at analyzing Rust code than rust-analyzer is. Not every language will have a language server that excellent, but I hope that'll improve for those users.