I definitely don't want to keep unused code in version control, but for debugging or for working on things iteratively as the sibling comment said, my Go code usually ends up peppered with

  if 1==2 { ...some code to temporarily disable ... }

"Just comment it out" is not always enough because when I want to quickly toggle the code on and off multiple times in a single session, it's not possible to do by only commenting/uncommenting that single block.

Sometimes the code that's commented out contains the only reference to an imported package, and by commenting it out the autoformatter helpfully removes the import from the top of the file, so then uncommenting the line is not enough -- I need to go back and re-add the import.

Or I may want to comment out this line

  x = f(a, b)

but that makes a and b in turn become unused as well, and I need to travel up to wherever they're defined and comment them out too, and so on with anything else that became thus unused in that chain.

And this is all suboptimal because the warning is also important when debugging. I do want to get warned about the unused code! Just let me compile.