While the top coding models have become much more trustworthy lately, Grok isn't there yet. It doesn't matter if it's fast and/or free; if you can't trust a tool with your code, you can't use it.
Not to mention that accidents happen, not everyone always has the good habit of using version control for every change in every project, and depending on the source control software and the environment you work in, it may not even be possible to preserve a pending change (not every project uses git).
I have heard real stories of software bugs causing uncommitted changes to be deleted, or causing an entire hobby project to be wiped from disk when it has not been pushed to remote repositories yet. They are good software engineers, but they are not super careful, and they trust other people's code too much.