post processing - What are non-destructive edits and do they exist?

This is going to be somewhat provocative and more about terms and definitions, so if you feel it should be closed or moved to meta, vote so.

To the question - there is a lot of talk about non-destructive edits that can be done during post-processing, but I'm a bit puzzled by the term non-destructive.

Edits to RAW file are said to be lossless/non-destructive, because original data is kept. But how can I call an edit non-destructive if data is lost in the result? Same can be said about JPEG - if I keep the original data, my edits are non-destructive because I can always go back to original (JPEG is a lossy format, but that's different story, we can as well talk about TIFF).

So there is a difference between lossless/non-destructive edit and lossless format, ie changing RAW to JPEG itself is destructive edit, because we lose information as the result. But we also might lose information in the result if we do WB adjustment to RAW file (the photo is bluish, we add more red and clip the red channel in the process).

Is the WB edit for example non-destructive in the meaning that we couldn't do any better in the same conditions originally? But what if we didn't take WB edit as non-destructive in the first place and used filters to get better data?

So what are the definitions of non-destructive and destructive edits?