Can't we have a system where we trade some performance for quick incremental compilation?

We can always compile with full optimization just before shipping?

The article gestures at (and the author has made a comment in this thread about) how this is the case for Zig. You are right that there is tension here, and so that's exactly what you do: accept less performance for the gains in incremental, and then don't do incremental for final builds. It's a fine way to go about it, assuming that the lack of performance doesn't make the program unusuable.

Of course we can, C++ even REPL and hot reloading tools.

The main issue is that so far such tools haven't been a priority for Rust.