Well, when I need to batch fix errors in files, yes it can take a while to run eslint. But that almost never happens. I have the plugin and fix errors as I go (which I believe is what most people do), and I never feel performance is an issue in this workflow. I really doubt how (actually) useful this is.
And once in a while that we have to run lint for entire repo (ESLint upgrade for example) we can afford to wait 1 hour ONCE
It's not that you can't wait 1 hour, it's that you don't have to wait. Think of all the wasted cycles that could be put to better use...
Quite hard, especially since type-aware rules from e.g. https://typescript-eslint.io/ mean that changing the type of a variable in file A can break your code in file B, even if file B hasn't changed.
If you lint the entire repo, fix every issue in one try on the first go, and then lint the entire repo to double-check, that's two hours.
But my workflow is usually: lint the repo -> fix one thing -> repeat