Yes, but precisely because of that there is a bit of resistance to people using that operation on large files, so it is not a common thing. It wasn't that long

Yes, but precisely because of that there is a bit of resistance to people using that operation on large files, so it is not a common thing. It wasn't that long ago that rewriting a 10GB file from top to bottom could easily take over three minutes (50MB/s write speeds to a spinning rust hard drive = 200 seconds, and if we account for also reading the file it will be even slower), so people tend to learn to program without asking for that operation. While there are many people who weirdly (to me at least) grotesquely overestimate the value of deduplication, it is legitimately useful because we tend not to want to completely rewrite large files very often like that, so even modifications to that file are very likely to either be appends or modifications of something in the middle without shifting the entire file.