One of my first jobs was at an investment bank. They had a lot of programs that ran overnight, in a batch fashion. Everything had to be done before the markets opened the next morning. The term they used for idempotency was "free rerun." Being able to rerun any program with no special setup work was a high priority.

The value in programs being a "free rerun" was that every so often the program would barf on a bad bit of data in a record.

The programming environemnt was interpreted BASIC, so if an error occurred the program would print a message on the console and drop to an interactive prompt.

The operators running the batch schedule would see this and call the programmer on call for that night. You'd log in (over dial up at this time) and attach to the process, look at the error, figure out what went wrong, either correct the data or (more likely) skip the record and deal with it the next day. It was more important to have the programs finish on time; individual issues could be dealt with later.

Often you could just start up the program from where it left off, but if things were more screwed up it was important to be able to re-run it without any negative consequence.

Edit: this was ~30 years ago, so my point is that it's not any kind of new idea or something that wasn't recognized long ago.