For languages like Rust, the language server does compilations — it has to run on the remote because it has to know about OS/arch-specific details.
There's a bit of latency between when you type and when the language server shows or hides the squigglies. But it's less than the time it takes to compile stuff anyway.
How often is my local machine going to have trouble running that? Having all that extra latency and bandwidth when I type sounds annoying.